Well, it does depend on what you're looking for, and how much work you're willing to put into it.
One option is to buy a very good replica of Boba's vest at roughly $70 from an experienced prop maker. Or if you have any talen with sewing, you could pick up some materials and create on yourself after modifying a vest-pattern. I've also heard of people using cut-off sweaters (with various results).
Well, think about it. How would armor look on a sweater ? If you say 'good' or 'I don't know', think for a longer period of time. When you arrive at ,"Pretty awful" or "Mediocre at best" you may stop thinking as you have arrived at a correct answer.
The truth is, limited resources create limited results. As with all things, do the best you can in the moment and improve as time and interest allows. As long as you're not kidding yoursef that you'll have an incredible Fett costume, you'll be fine. Yet, you will have an adequate one. We all start somewhere.
Yeah. A good quality sweat shirt, with the sleeves trimmed and hemmed properly would probably suffice. Just try to find a shirt with thick material and of the color you are really looking for. It would probably work well, if done with care and attention to detail.
My current plan is to use a modded sweatshirt to make a pattern that I will cut out from a few pieces of "pleather" material and sew the sweatshirt in between two layers of the "pleather". This will give my vest a thick, "kevlar" look.