My first buying experience on e-bay, many years ago, was autographed sports photos for my nephew. I bought many of them, some appeared authentic, with better validation, but most of them were questionable and some were definitely not authentic originals. After I had made these purchases, there was a very
big brouhaha about phony items of that type being sold on e-bay and by the major sports memorabilia dealers in Las Vegas as well. On balance, I felt I had thrown out a great deal of money because I was uncertain about authenticity. This was quite some time ago, before they had things like numbered and tamper-evident holograms.
I also purchased a few autographed items from QVC, and those did appear to be authentic. I suspect that the major shopping channels make some effort to check out the reliability of their vendors, and the authenticity of their merchandise, so you might consider the vendors they use.
I just looked on the QVC Web site, and they currently only have a handful of items, but the items are from either Mounted Memories or Steiner Sports. I also just checked the Home Shopping Network, which has many more items, all of which seem to be from Steiner Sports.
If I were you, I'd check out those two vendors--the major shopping channels have too much to lose by dealing with less than reputable vendors. I'd feel more confident buying from one of these vendors.
You could also check the Home Shopping Web site (HSN.com) to see if, by chance, they have what you are looking for.