Neonhusky has the best variety. However I have had a few problems with them. First order, the ball had specs of concentrated dye inside of it, as well as a small raised area on the ball. When I contacted them, they said they were aware of the problem and that they had had complaints about it before - meaning it's a consistent problem with their manufacturer. The second order consisted of 3 UV balls and 1 lemon-lime ball of the same size. The lemon-lime was slightly larger, and, again, they said they were aware of this problem. Now, it's not a huge deal as far as how it LOOKS goes, but it's quite noticeable despite how small the difference is when they're actually in your hands and is a bit of an annoyance when using them. As well, one of the UVs was an ugly green tint. HOWEVER, they fixed the problems: first order, they gave me 10 bucks off my next order; second order, they sent me a new UV ball for free.
<- Bob's magic shop has a good variety and VERY VERY good prices, you won't find anything cheaper. If you're new, then go here; there's no sense in getting expensive balls at this point because I ASSURE you they WILL get scratched up no matter how careful you are. The balls are very good quality for their price. The clears are SLIGHTLY dull and the UVs don't have the pretty blue bubble-like hue in morning light like most UVs, but I'm quite happy despite this. I've heard that sometimes people find their balls have small debris in them, but I haven't had this problem.
Also, check out contactjuggling.org ... best place to go for CJing.