Absolutely.  Any eBay seller is by definition a software pirate.  At best, they are selling a legitimate CD that they bought and can't use, which is a violation of the license but probably won't hurt you.  Or, they installed the CD and are then reselling it, which is stealing from Intuit.  Anyone on eBay who is offering a software download is definitely a pirate and could be selling the true software, or software contaminated with viruses, or they could just take your money.

There is a very limited number of official resellers for the download, places like Staples, Amazon, and direct from Intuit.  More places sell the CDs, like Walmart, Costco, Target, Best Buy, and others.  Stick with a brand name retailer you recognize.