i have bought from about 30 different ebay vendors. I have had problems with one, others have been great. several have replaced dud eggs. communication is the keyYou have only mentioned the two experiences above. One ebay one byc. Two is not a very big sample size to judge either source if you are thinking to buy at only BYC or only off ebay.
I too have had good sellers, and poor sellers. ANd all from BYC. Don't give up, keep enjoying he process of buying eggs and hatching little cuties.