Step one: get more money....
Well seriously, if you're going to buy costume pieces, it'll cost more (and be fair to somebody who worked hard to make it and deserves not to starve).
My wife is planning to order from Jedi Closet on Etsy, and it'll cost about $150 for tunic/obi. She'll need a jedi belt (already has boots and leggings).
Conversely, yesterday, we just did an event at Alamo Draft House, and made her up with a tunic shirt she had, leggings, boots, arm wraps she already bought, normal belt, and a sleeveless cardigan with hood we ordered and arrived hours before we headed out. Women's clothes tend to have modern stuff that could pass muster. (but not SaberGuild standards, just close enough to fool the average person).
Here's the men's cardigan on Amazon:
https://www.amazon.com/gp/product/B07Q19XFFJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1Here's the wife in that costume:
Individual clothing pieces are going to be $30-$100+ a piece. Boots, at least $50, probably $150.
One of the jedi I was with used a pair of tan Dockers trousers. Looked fine. So there's some menswear that you might re-purpose
If you can make your costume, fabric is a ton cheaper. There are a few posts I've seen in the last year where they did that (some their first time and it worked well). So don't let that scare you off.
And you don't have to get it all at once. So you have $100, right now. Keep saving, watch for deals and order pieces. Study the SaberGuild site on custume specs AND pics of characters from the movies. See the layers of clothing and pieces and think about what you've seen that might be like that (like that cardigan above). SG is a good reference point, even if you don't follow it strictly it will remind you of costume elements you should be thinking of.
https://saberguild.org/costume-standards/Also, that handsome Sith in the background is wearing RenBoots with piratey folded top, baggy pirate trousers and a t-shirt under that black and red tunic. And driving gloves. I borrowed the tunic/obi/belt from another member sight unseen, had no idea it didn't have sleeves. Nobody knew.
So raiding the ren-fair section of the closet can help. We are space-wizards after all