The main problem is that hardly anything is selling at the moment, people are financially terrified. What might be considered a "fair" used price according to somebody who paid retail, is far from the price that people are willing to pay in reality at this time. "Fair" has no meaning in pricing right now.
Now, that said, this particular amp is further handicapped sales-wise. I apologize in advance that this may sound too mean, but it's the truth as far as I see it:
On the Eden forum, an Eden rep stated the only difference between the "new" version and the "old" one is cosmetics: Tolex instead of rat fur, and a light-up Eden logo. I'm not sure what brainiac at Eden thought the reason nobody bought the 300T was because it didn't have a light-up logo.

The two real reasons are: (1) David Nordschow was the foundation of Eden, and he had nothing to do with this amp; and (2) it's a rebranded Chinese generic item. Now, to be fair, David isn't the end of the line as far as amp design--just because David left (or was fired?) doesn't mean the new Eden managers couldn't have hired their own engineers to come up with a great amp. But they didn't, anyway. And again to be fair, just because something was made as a generic product and then cosmetically repackaged for the US market doesn't inherently mean it's not a great amp--it might very well be a terrific amp! But the stigma is there, and the Chinese rebranded item is a stark reminder of Eden fans' general disappointment in where Eden has gone in the last few years.