Depending what you currently have you may need a different boss (or just an adapter).
I'm in a similar boat. I'm really liking the nardi wheels. Driftworks has a quite decent selection.
Regarding what fits,it's just down to the boss that you have, there's only 2 common bolt patterns, MOMO or Nardi. You can get adapters from one to the other quite easily (Some bosses will be drilled for both)