Does anybody know where I can by different types of fisheye lenses? And where I can learn what the differences are? Everytime I search it on yahoo I get a bunch of links for sites that are selling the camera I'm buying the lens for.
(I'm looking for the ones that really distort the horizon a lot without vigneting)

did u try searching amazon?

Check local camera stores. I actually have had good luck purchasing new lenses on Ebay. They're significantly discounted, brand new, and sold by NYC photo stores for some reason. Watch out for scams though.