to be honestly, i only go to wheel/tire companies for tires or for some really rare wheels that cant be found anywhere else. The best wheels out there are wheels that people already own. if you dont mind used wheels, i say check out zilvia.net. there are a lot of 240sx guys that run all kinds of hard to find JDM wheels that are also applicable for our cars. I scored some SSR SP1's deep dish wheels from zilvia for dirt cheap. If i were to order straight from SSR, it would have taken 3 months to arrive from japan and cost 3 times as much as a got them for.
if your dont want to go that route, it depends what brand wheels your looking for? it will narrow different places that offer a certain wheel. TireRack is good, but sometimes limited in sizes and offset. You just have to search around i guess.