I've done that too and if the price is right they are a good deal, except the no name Chinese ones. There was a bit test done by Fine Woodworking about 8 yrs ago that can be googled and downloaded for free. Interestingly, neither Freud, CMT, or Amana scored well even we all consider them good bits. Some of the ones that beat them were BC Saw, Lee Valley, Infinity, Rockler, Eagle America, and Whiteside.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.