I bought 2004 LT on E-bay and it was a copy made to be given away at trade shows (a "Promotional Item" with a generic serial number). I couldn't register it, and it was not acceptable for the upgrade to 2005. AutoDesk wouldn't even talk to me about it.
This product looks like it is legit and his ad answers all of the questions that I tell people to ask.
You have to wonder about the other sales under "AutoCad 2006" that are listing it for 9 GBP. My daddy always said that if a deal looks too good to be true then it probably isn't.
David