you can ask a vendor/ jeweler to order you some some earring mounts from Stuller or adwar...
but I have bought from Tripps before, not earrings though, their finish is ok, you may need to get it polished up a bit more though. These are usually settings for calibrated stones. if you have an interesting size, it may or may not work. They were pretty good about exchanges (even though my window was already closed for a refund)