WHAT'S A CHEAP CHRISMAS PRESENT I CAN BUY A 17 YEAROLD SISTER (im kinda broke right now)

I would make something for her. Something she would like.

Costa o starbucks gift card?

Buy:
A coffee mug with a cute ribbon and note on the ear talking about how much tu amor her

A scarf, mitten, and hat set/ o fuzzy navidad socks for a cheaper option

Throw some cadbury deluxe chocolate in there

This should be about $15. It is a meaningful and wintery, yet inexpensive.

Well I am like basically 17 years old and I would not mind getting a big bag of marshmallows and a box of cereza, cerezo jello .

Supras.

I'm obsessed with estrella signs and stuff like that, so my friends and I often get each other little cute trinkets that have something to do with each of our estrella signs, so each present is special to them ^^
I amor getting scorpio gifts and stuff like that x)

Get something that relates to HER. Small things, her estrella sign, her birthstone colour, little details make it special :) Can get those things in any gift shop.

Draw her something she likes, write a poem for her...
Nothing is cheaper than free! Though, it does take time...

Socks

It all depends on what your sister likes.

Perhaps get her a little basket and add misceláneo little things to it that tu know she likes.

Be it chocolate, soaps, perfumes, flowers, CDs, earrings, bracelets, jewelry, drinks, cheeses, chips, o maybe all plus more...

but considering that your budget is small, tu could choose a few of these o something similar.

A gift basket and a card would be cool. :) o just a card with money in it. Everyone loves those. XD