Take a look at this thread here.
This is the problem. People that don't do their research before dropping this kind of cash on a card. $150 isn't a ton of money, but it is enough incentive for a scammer to do this.
Here is how the buyback scam works:
1. Pick a star card, any star base rookie card.
2. Look at any sample of player's auto.
3. Practice signing a piece of paper.
4. Practice signing on a couple of commons
5. Sign the card
6. Hand Number the card.
7. Create Ebay listing.
8. Collect money from suckers.
Extra Special Bonus Points: Use a run of the mill case and put a silver foil sticker to "seal" it.
Here is my view. Unless you can verify 100% that the card is legit, don't bid. Remember, compare to known authentic sigs like the rest of us. Unless it right on.... Also, anyone can fake these. Anyone can remove a sticker from a scrub and use it on the card. Anyone can get a hologram and place it on the card.