A word to the wise. With a very narrow exception (see below), you cannot "purchase" a used H20. They all belong to D*. If you buy one from someone on eBay, it is very likely stolen or should have been returned to D* and wasn't. (Same thing.) When you go to activate it, you lose.
The narrow exception is that when they first came out - early January 2006 I believe until March 1, 2006 - they were available for purchase. I did so. Most of those boxes were purchased with a rebate from D* that required the H20 boxes to be returned to D* if you canceled your subscription. I did that, too, so I know from experience. (Leaving was a mistake and I have been back with D* for 15 months now.)
H20-600 HD STBs now have been recalled by D* That was the model first issued. (They ran too hot and are now considered defective.) That's a further impediment to "buying one." All subsequent models such as the H20-100 are leased only. They were never offered for sale. No one "owns" one so no one can sell one.
Sorry to pound on this subject but I presume no one wants to throw their money away.