I often pick up cards that the seller doesn't know about; a benefit of being into some niche items. However, on the risk-reward scale this is one that comes to mind:
I'd been looking for a Dr. J RC for a while and came across this one, raw, for $90. I assumed it was possibly trimmed, damaged, fake, whatever, but the seller was local and there was the eBay/PayPal refund thing so I took the risk. The card looked great, measured out, etc., so I sent it to PSA and got back the 8. Still have it, BTW.