I purchased Acrobat Pro some time back from Ebay, and it worked fine with a few updates for a few months.
Then Adobe caught on with these illegal copies, and my license was no longer good.
The copy was from EBAY from a 70+ positive feedback seller. I paid over $120 for it. the sw came in a very professional OEM looking Adobe box and everything.
I usually buy direct from Adobe, and they keep the file in your account for DLs. But this looked really good :-)
You said it...if the deal is too good to be true....