Has a large selection of high quality sealed bearings. They probably have the size you need. Take some measurements of it, or read the numbers on it, and give them a call.
They've done right by me.
As a note: do ask who makes the bearings you're buying. There is a big difference between a quality ball bearing and a cheap one, and there's no way to tell by looking at them. Truth be told, price is usually a good indicator, presuming you're getting them from similar sources (industrial supply places).