I looked at kustomkoozies.com for ours, but since the wedding is still kind of far I haven't ordered anything yet. Every single site I've found lets you order in bulk, though.
We ordered our koozies from http://totallyweddingkoozies.com, and we love how they turned out! We shopped around the different website quite a bit before ordering, and we thought they offered the cutest designs and the lowest prices. They even threw in a free set of bride/groom koozies, which I just thought was so cute!
Re: Koozies