I've been experimenting with Si[SUB]3[/SUB]N[SUB]4[/SUB] Ceramic Silicon Nitride bearings from E-Bay. For enough to build a couple of hubs, they aren't too expensive.

So far I've been happy with them, but I won't really be able to judge for another year or two.

One of the problems with steel bearings is the quality is so variable. I periodically find bearings where it apears as if a thin chrome layer has just pealed off from the bearings, leaving a mess behind