I have sold bats on ebay for prices that I would never have let things go for, because they did not have a COA. I'm talking about bats right out of the players hands, well used, perfect for collecting type bats that I wish I still had. This is why the guys who are smarter than me put reasonable reserves on items. But even then, without COAs, nobody bids on them and you're now stuck with ebay fees and you take the loss. I can't tell you how many times I have put a bat on ebay or on this site and 9 of the first 10 people responding ask me if there's a COA. Not, "Where did you get this" or "How did you come by this bat", but instead, "Does it have a COA?" I have a folder full of COA's because other sellers gave them to me when I bought bats. I used to take those little holograms and rip them off of items when I got them because I hate the way they look. Now, I leave them on in case I decide to move one just because everyone else seems to want them.