hey jrcastro. I know you said you don't want to buy from an LFS, but seaside actually has some nice ones for a good price. There's nothing wrong with buying from a LFS, just make sure the fish eats and hasn't been sitting in the tank for a while. Also, the most important thing is the acclimation. I drip acclimated my pbt for almost 2 hours before putting it in the tank and now its colored up quite a bit more and eats everything I throw in the tank.
edit: They have some nice purple tangs. Not sure about yellow, but pretty much everywhere has yellows.