Q: I need to swap out my turbo before it's shot and I was wondering what are some good brands that will give me performance and reliability. I don't want to spend over $500
A: If your willing to buy used, factory subaru IHI turbo's are a dime a dozen. A used vf39(STI Turbo) can be had for anywhere from 300-400 dollars and is direct bolt on (most VF** are). You won't find any aftermarket turbo's in the price range you're looking for new (or used really). But, you also need to calculate in tuning and supporting mods, the VF39 is one of the most common swaps for a wrx but you at least need the 565cc (STI pink) injectors, plus a tune, those will run you about $200 used (this alone will throw you over the budget). Then tuning, you can always go open source ($85 for the cable) and DL a XPT map to your ecu, or buy a Cobb AP ($695 new, 300-600 used) with a staged VF map. Either way you're already far over the budget, and these cars CANNOT get away without a tune of some sort for something as crucial as a turbo swap. If you're really on a budget I would just look into buying another stock or mildly ported TD-04, used/rebuilt will easily fall into your price range with no real other costs save for gaskets, labour and such. Unfortunately to say, a turbo upgrade is not something you really do on a tight budget, even when a turbo says "bolt on" there's always other variables to consider as well as room that should be left in case suprises crop up.