Odds on that its a HAgrid/Fluffy... the thinner and rarer insert cards (letters, frog, stone) would be discernible if you knew what you were looking for, although you might be lucky
I reckon with these types of auctions, don't pay more than you are willing to pay/gamble for a low value/high numbered card. I bought a TTU one and got a Faramir, I paid slightly more than what I would have for the card itself, but it was worth the fun of the gamble!
This seller is soccerfanatic who used to post here occasionally if my memory serves me correctly
