The ones on eBay are usually grey market merchandise... Its a safer bet to get the item from the store because of warranty issues at most places you can extend the warranty up to 5 years for under $50.00. However if you don't think you will encounter any problems with the unit than eBay is always going to be the cheapest.

Employees get the unit at cost at Circuit City and Best Buy. You can look for someone willing to use their discount for you. Most people will do it if you hand them a Ben Frank...