Learn Hardcore Croatian: Ne volim kupovati skupe stvari svaki dan, radije kupujem samo što trebam. - I do not like to buy expensive things every day; I prefer to buy only what I need.

voljeti + infinitive (volim kupovati) = to like (doing something) as an activity / habit
- Ne volim kupovati skupe stvari. = I don’t like buying expensive things (in general).
sviđati se + Dative (sviđa mi se) is usually about:
- things, people, situations that are pleasing to you at a particular time:
  - Ne sviđaju mi se te skupe stvari. = I don’t like those expensive things.
  - Ne sviđa mi se kupovina. = I don’t like shopping (the concept/experience).

So for “I don’t like buying expensive things (as a habit)”, ne volim kupovati is the natural choice.
Ne sviđa mi se kupovati skupe stvari is understandable but sounds a bit more like “buying expensive things is not pleasing to me”, and is less idiomatic as a general statement of preference.

Why is it kupovati and not kupiti?

Croatian has aspect:

kupovati – imperfective (ongoing, repeated, habitual actions)
kupiti – perfective (one completed action or a specific act)

Here the speaker is talking about a general habit:

Ne volim kupovati skupe stvari svaki dan.
→ I don’t like buying expensive things (repeatedly, as a habit).

If you used kupiti, it would sound like talking about a single, concrete purchase:

Ne volim kupiti skupe stvari.
→ This sounds wrong in standard Croatian in this context, because voljeti
- perfective infinitive is unusual for a general dislike.
  Perfective infinitives are more common with verbs like morati, trebati, htjeti (e.g. moram kupiti, želim kupiti).

So here kupovati is correct because the sentence describes a repeated action (“every day”).

What form is skupe stvari, and why not skupih stvari?

Skupe stvari is:

stvari – feminine plural noun, Accusative (direct object of kupovati).
skupe – feminine plural adjective, Accusative, agreeing with stvari.

In Croatian, for inanimate feminine nouns, Nominative plural = Accusative plural, so:

Nominative: skupe stvari
Accusative: skupe stvari

We use the Accusative here because we are directly buying those things:

(Ja) kupujem skupe stvari. – I buy expensive things.

Skupih stvari is Genitive plural and would be used in different structures, for example:

Ne volim cijene skupih stvari. – I don’t like the prices of expensive things.
Puno skupih stvari – many expensive things.

So skupe stvari is correct as the direct object of the verb.

How do I know stvari is feminine, and how does skup- agree with it?

You infer it mostly from common patterns and dictionary knowledge:

stvar (singular) ends in -ar, but its plural stvari ends in -i, and it’s grammatically feminine.
Adjectives must match the noun in gender, number and case.

Singular:

Nominative: skupa stvar (one expensive thing)
Plural:
Nominative: skupe stvari (expensive things)
Accusative: skupe stvari (same form here)

The adjective skup behaves like a regular adjective:

Masc sg: skup
Fem sg: skupa
Neut sg: skupo
Fem pl: skupe (used in skupe stvari)

What does svaki dan mean, and how is it different from svakog dana?

Both are common and both mean “every day”, but the grammar is slightly different:

svaki dan
- svaki – “every”, masculine singular, Nominative
- dan – “day”, masculine singular, Accusative
- In this time-expression, Accusative is used adverbially to mean on (each) day.
svakog dana
- svakog – “every”, masculine singular, Genitive
- dana – “day”, masculine singular, Genitive
- Literally “of every day”.

In practice:

svaki dan = every day (very common, slightly more neutral/colloquial).
svakog dana = every day (equally correct, sometimes sounds a bit more formal or literary, but often interchangeable).

In this sentence, svaki dan is perfectly natural:
Ne volim kupovati skupe stvari svaki dan.

Why is there just a comma before radije kupujem, and not a word like ali (“but”) or nego?

The Croatian sentence:

Ne volim kupovati skupe stvari svaki dan, radije kupujem samo što trebam.

has two clauses separated by a comma. In English we’d usually use “but” or a semicolon; in Croatian, just a comma is very common in everyday writing for closely related clauses.

You could add a conjunction:

… ali radije kupujem samo što trebam. – “… but I’d rather buy only what I need.”
… nego radije kupujem samo što trebam. – possible, but with nego you’d usually contrast two explicit options (e.g. “ne ovo, nego ono”).

The plain comma is fine in informal style and clearly implies contrast here. In more careful writing, ali would often be added.

What exactly is radije, and how is it used?

Radije is the comparative form of the adverb rado:

rado – gladly, willingly
radije – more gladly, rather, preferably
(superlative: najradije – most gladly / preferably)

Usage:

Radije kupujem samo što trebam. – I’d rather buy only what I need.
Radije pijem čaj nego kavu. – I’d rather drink tea than coffee.

Structurally, you can think of it like English “rather” or “prefer to” in many cases.

What does samo što trebam literally mean, and why not samo ono što trebam?

Literally, samo što trebam is:

samo – only
što – what / that which
trebam – I need

So: “only what I need”.

In fuller, slightly more explicit form, many speakers would say:

samo ono što trebam – literally “only that which I need”.

In everyday speech, ono is often dropped when the meaning is clear, so samo što trebam is perfectly natural and a bit more concise.

Both are correct:

… radije kupujem samo što trebam.
… radije kupujem samo ono što trebam.

Why is it što trebam and not što mi treba?

Both are possible, but they have different structures:

što trebam
- što = what (object)
- trebam = I need (subject = I)
  → literally: “what I need”.
što mi treba
- što = what (subject)
- mi = to me (Dative)
- treba = is needed (3rd person singular)
  → literally: “what is needed to me”.

Meaning-wise, both end up as “what I need”, but:

što trebam emphasizes I as the one needing.
što mi treba emphasizes the things that are needed to me.

In this sentence, both could be used:

radije kupujem samo što trebam.
radije kupujem samo što mi treba.

The original just chooses the simpler trebam-construction.

Why is it trebam and not something like trebam to here?

The object of trebam is expressed indirectly via što:

što trebam = what I need

The “what” (the things) is already included in što, so you don’t add to:

Treba mi to. – I need that. (here to is a specific “that”)
Trebam to. – I need that (colloquial, subject = I).
Trebam ono što imam. – I need what I have.
Trebam što trebam. – (odd but grammatically: “I need what I need.”)

In samo što trebam, što itself plays the role of the object, so trebam doesn’t need another pronoun like to.

Why is there no ja (“I”) in the sentence?

Croatian is a pro-drop language: subject pronouns are usually omitted because the verb ending already shows the person.

(Ja) ne volim kupovati…
(Ja) radije kupujem…

The -m ending in volim and kupujem clearly shows 1st person singular, so ja is not necessary.

You would include ja mainly for emphasis or contrast:

Ja ne volim kupovati skupe stvari svaki dan, ali on voli.
– I don’t like buying expensive things every day, but he does.

Could I say Ne volim skupe stvari kupovati svaki dan? Is that word order okay?

Yes, that word order is grammatically correct, but the emphasis shifts.

Ne volim kupovati skupe stvari svaki dan.
Neutral focus: you don’t like the activity of buying expensive things every day.
Ne volim skupe stvari kupovati svaki dan.
This puts a bit more focus on skupe stvari (expensive things) – it can sound like:
- “It’s those expensive things that I don’t like to buy every day.”

Croatian word order is flexible. The original order (kupovati skupe stvari) is the most neutral and typical, especially for learners, but changing it is often used to highlight certain elements.