Ok so straight out the gate i should tell you there are a fair few long standing favorite CHEAP EATS in Melbourne.
The first is the famous Don Dons, on Swanston street just near Melbourne Central (however they are like the Leaky Cauldron: you only see it if you know its there). It definitely gives you bang for your buck, and not in a St.Kilda way. They have a pretty short menu, with about eight items. You can get Miso soup, Teiyaki chicken, that sort of thing for a very reasonable price. Another great thing about Don Dons is you get served almost before your in the place and you get your food maybe thirty seconds later.
This place do like their salt however. But, if you can get an entire "Don Don box" for Eight bucks, you dont really care do you? No. This bento box has fruit and chicken and beef and is pretty delectable. Another slight negative is that the place is the size of a shoe box and a fair few people know about it, so expect to fight tooth a nail not just to get a table but to keep it. I had to share a table for two with two other people. Yep, awkward.
Hint: to stretch a budget just that little bit further order the takeaway. They always give you too much so have the leftovers for lunch the next day. Or breakfast, in my case.