Learn Hardcore Indonesian: Saya membeli aksesori telepon murah di pasar. - I buy a cheap phone accessory at the market.

membeli is the active verb formed with the prefix meN- attached to the root beli (buy). It marks an active, transitive action and sounds more formal/neutral. In everyday speech, dropping the prefix is very common: Saya/Aku beli aksesori... is perfectly natural. (Phonology note: with roots beginning with b, meN- surfaces as mem-, hence mem+beli → membeli.)

Does murah describe the accessories or the phone?

Here, murah follows the noun phrase aksesori telepon, so it describes the accessories: “cheap phone accessories.”
To say “accessories for cheap phones,” use something like:

aksesori untuk telepon yang murah
aksesori untuk HP murah To make it crystal clear the accessories are cheap, you can also say:
aksesori telepon yang murah (the relative marker yang ties “cheap” to the whole “phone accessories” phrase)

Why is the adjective after the noun?

Indonesian adjectives typically come after the noun they modify.

baju baru = new shirt
kota besar = big city
aksesori telepon murah = cheap phone accessories Putting the adjective first (e.g., murah aksesori) is ungrammatical.

How do I show past, present, or future if there are no tenses?

Use time/aspect words:

Past/completed: Saya sudah membeli...; Kemarin saya membeli...
Ongoing: Saya sedang membeli...
Future: Saya akan membeli...; in casual speech, Nanti saya beli...

What’s the difference between di, ke, and dari?

di = at/in (location): di pasar = at the market
ke = to (direction): ke pasar = to the market
dari = from (source): dari pasar = from the market

Is aksesori singular or plural here? How can I make it explicit?

Indonesian doesn’t mark plural by default, so aksesori can mean one or more. To be explicit:

One: satu aksesori (telepon) or sebuah aksesori (acceptable but less common)
Some: beberapa aksesori, banyak aksesori
Emphatic plural (more formal/written): aksesori-aksesori

Can I omit anything in casual speech?

Yes, commonly:

Drop the prefix: Saya/Aku beli aksesori telepon murah di pasar.
Often the subject is omitted when context/time makes it clear: Tadi beli aksesori telepon murah di pasar. (Earlier [I] bought…)

Can I move di pasar to another position?

Yes, for emphasis or style:

Neutral: Saya membeli aksesori telepon murah di pasar.
Location focus: Di pasar, saya membeli aksesori telepon murah.
Another acceptable variant (more written): Saya di pasar membeli aksesori telepon murah.

Is telepon the right word for a mobile phone?

telepon = phone/telephone (generic)
HP/hape = mobile/cell phone (very common, informal)
ponsel = mobile phone (neutral/formal) For everyday talk, you’ll often hear aksesori HP.

Is aksesori the same as aksesoris?

The standard (KBBI) spelling is aksesori. The variant aksesoris is very common in shops and casual writing. Both are widely understood; use aksesori in formal contexts.

How would I say “I bought it at the market” referring back to the accessories?

Use the clitic -nya or a passive-style sentence:

Saya membelinya di pasar.
Short passive: Aksesori telepon murah saya beli di pasar.

How do I say “cheap” as in low-quality?

Use murahan for “cheap/low-quality/trashy.”

Aksesorinya murahan. = The accessories are cheap (in a bad way).
Use murah for “inexpensive” without a negative judgment.

Any spacing pitfalls with di here?

Yes. As a preposition, di is written separately: di pasar. As a passive prefix, it attaches to the verb: dibeli.
Wrong: dipasar. Right: di pasar / dibeli.

How do I make comparisons like “cheaper” or “cheapest”?

Comparative: lebih murah = cheaper
Superlative: paling murah or termurah = cheapest
Examples: Di pasar itu, aksesori telepon lebih murah. / Toko ini yang termurah.

How does the noun + noun pattern work in aksesori telepon?

Indonesian allows a noun to modify another noun directly; the head comes first.

aksesori telepon = phone accessories
tas laptop = laptop bag Don’t reverse the order (e.g., telepon aksesori) when you mean “phone accessories.”