Learn Hardcore Indonesian: Kemarin saya beli jam tangan murah di pasar. - Yesterday I bought a cheap watch at the market.

Indonesian commonly uses the base verb in everyday speech. beli (base) and membeli (with the meN- prefix) both mean “to buy.” Your sentence is natural and conversational. A more formal version would be: Kemarin saya membeli jam tangan murah di pasar.

Can I drop saya?

Yes, in casual speech the subject can be omitted when it’s clear from context: Kemarin beli jam tangan murah di pasar. In writing or when clarity matters, keep saya.

Where can I place kemarin?

Flexible. Common options:

Kemarin saya beli jam tangan murah di pasar. (time first; very natural)
Saya kemarin beli jam tangan murah di pasar.
Saya beli jam tangan murah di pasar kemarin. (fine; can sound like “at the market yesterday”)
Di pasar kemarin saya beli jam tangan murah. (more like “at yesterday’s market,” e.g., a specific market day)

Avoid di kemarin; preposition di doesn’t go with days/time words like that.

Do I need sudah to mark the past?

No. Indonesian doesn’t require tense marking if a time word like kemarin is present. Sudah adds the nuance of completion/already: Kemarin saya sudah beli... = “I had already bought...”

Why is murah after jam tangan?

Adjectives usually follow the noun in Indonesian. So jam tangan murah = “cheap watch.” Putting it before (murah jam tangan) is ungrammatical. As a predicate it can come after a copula-less subject: Jam tangan itu murah.

Do I need yang before murah?

Not here. jam tangan murah is a simple noun + adjective. jam tangan yang murah tends to be more specific/contrastive: “the watch that is cheap (as opposed to other, pricier ones).”

Is the sentence singular or plural?

By default it’s number-neutral. It can mean “a watch” or “(some) watches.” To be explicit:

One: Saya beli sebuah jam tangan murah... / Saya beli satu jam tangan murah...
Several: Saya beli beberapa/banyak jam tangan murah... or jam tangan-jam tangan murah (reduplication).

Should I use sebuah here?

Optional. sebuah is a generic classifier and works well: Saya beli sebuah jam tangan murah. It also prevents any fleeting confusion with satu jam (“one hour”). Satu jam tangan is also fine, but sebuah is very natural.

What does di mean here, and how is it different from ke and dari?

di = at/in/on (location): di pasar = “at the market.”
ke = to/toward (movement): ke pasar = “to the market.”
dari = from (source): dari pasar = “from the market.”

Can I omit di pasar?

Yes, if the location is not important or already understood: Kemarin saya beli jam tangan murah.

Is jam tangan the normal way to say “watch”? Any alternatives?

Yes, jam tangan is the standard term for a wristwatch. jam alone can mean “clock” or “time.” A more formal/older word is arloji: Saya membeli arloji murah.

What’s the difference between kemarin, tadi, and barusan?

kemarin = yesterday (often also “the other day” in casual talk).
tadi = earlier today.
barusan = just now.

Should I use saya or aku?

saya: polite/neutral, safe with strangers and in formal contexts.
aku: informal/intimate, with friends/family. Regional colloquials exist (e.g., gue/gua in Jakarta), but they’re dialectal.

What’s the typical word order for time and place?

Common and clear:

Time first: Kemarin [S] [V] [O] [Place].
Or place last: [S] [V] [O] [Place] [Time]. Indonesian is flexible, but avoid placements that create ambiguity (e.g., di pasar kemarin can imply a specific “yesterday’s market” event).

How do I negate this sentence?

Simple negation: Kemarin saya tidak beli jam tangan murah di pasar.
Informal: nggak/ngga/ga instead of tidak.
“Not yet”: belum (e.g., Kemarin saya belum beli... is odd; use belum for present relevance). Use bukan to negate nouns/pronouns, not verbs.

How would a passive or fronted-object version look?

Short passive/object fronting (very natural): Kemarin jam tangan murah itu saya beli di pasar.
Full passive: Kemarin jam tangan murah itu dibeli oleh saya di pasar. (more formal, less common in speech) Note: Saya dibelikan jam tangan... means “Someone bought me a watch,” a different meaning.

Any spelling notes about di?

As a preposition, di is written separately: di pasar. As a passive prefix, it attaches to a verb: dibeli. Don’t write dipasar or di beli in this sentence.

Does murah carry a negative connotation?

Not inherently; it means “inexpensive/cheap (in price).” murahan is pejorative (“cheap-looking/tacky/low quality”). For positive tone, you can say terjangkau (“affordable”): jam tangan yang terjangkau.