Well, here's my personal read on the issue...
The seller gave us a really nice price with the understanding that they were going to end users, not so they could be resold on eBay. I think that if you were to buy one and then list it on ebay just a few weeks or a month later, then that would be contrary to the spirit of the agreement. On the other hand, if after using your unit for six months or a year you decide you want to sell it, I believe that's an entirely different thing. At that point you are clearly selling a used unit that you bought for personal use, not for resale. I think he realizes that eventually some used units will turn up on eBay from time to time; that's not the issue.
Of course I can't actually control what you do. But you will note that while I mentioned that I have some units left over from the group buy, I am not (and will not be) putting them on eBay.
Then again, I don't think you're likely have much trouble selling your unit if you decide to do so, with or without eBay. This is a $3300 computer with an incredible "cool factor" for under $400. Bill Gates is convinced that there are literally a million people out there who will pay him $1200 for a similar unit. If you can't find just one person who will pay a fraction of that price, then Bill has some serious trouble ahead.