http://stores.ebay.com/The-Morezmore-Estate_6-DECORATE-FINISH/_i.html?_nkw=eyes+seconds&_fsub=14944039&_sid=58601371 These are the best I've found so far. I've found other dealers for the same eyes but as they mention they vary in shape, color and pupil placement. So these that have been presorted to match each other are the best I've found - though these are only this seller's SECOND BEST eye pairs, they also have slightly higher price listings for perfect matches.
I have a pair of these 3mm brown second best on their way to experiment with myself :D
That should be a listing for all colors from 2mm and up, 3 pairs each, though they have not been pre-sorted for best results.
Set of 3, 4mm glass-like eyes in the common colors (brown, blue, green). Since those are probably hand made by the seller they might be able to accommodate additional colors or sizes.
I hope one of those is helpful!