Things that cost money generally make it more comfortable and easier to pass, but with the exception of binders for large chested guys, a lot of the time you don't need to buy anything really.
I'm fortunate to have quite a masculine face, but also I'm incredibly short, 4th shortest in my school year (and two of them are the shortest people I've ever seen without having dwarfism) so my chances of passing are probably about the same as anyone's, and for a variety of reasons I don't do anything other than dress how I want and act how I want and I pass. The only time I think about mannerisms is when I'm being seen as male by one person and everyone else around me knows me as female, I try to actively pass so they don't realise and draw attention to thinking I was male by correcting themselves.
I also know what it's like to have had more money than you do currently, we used to have money but now we don't, for reasons out of our control. When things like that happen you've just got to swallow your pride and adjust the way you've been used to living. For you that might mean selling everything that isn't necessary or often used (you'll be surprised how much you don't need, I'm clearing out to move and have filled about three boxes already of stuff I want to sell) and changing where you shop. I live in the UK so I don't know what sort of places you have to shop in over there, but just look around, you can get some pretty good deals if you look around.