I bought one crib sheet at Pottery Barn Kids. Love it! I think I might have to make a crib sheet for our boy. I want a tropical fish one that's actually blue (not white with fish) and I can't find one. I'll have to fashion something out of fabric from the fabric store.
Re: Shopping for bedding
Take a peek at Baby Bargains for good manufacturers before you go shopping. It's really eye opening.
We got ours at Baby Depot.