Well,
I won't give you the search spewl, but there are a lot of old threads on this topic. Two common upgrades that are inexpensive are the 16" wheels from the FD RX-7, and the 17" MKIV TT wheels. Outside of that, the aftermarket is really strong for the car because just about anything that will fit a MKIV will fit a MKIII. The only thing you have to be careful on is the rear fitment. If you go up to a 10" wheel, you can't go under 40mm without having rubbing issues. +38 might work, but I can't garauntee that...
If you want to go the cheap and clean route, consider either the RX or the MKIV wheels. Both look nice and are clean.
- Hams.