This is pretty silly. You advertised an "original" debug kit. The 'bonus' switch (which is a dead give away that it is not legit) was not mentioned, and not pictured. A debug kit case with retail mobo might be worth $450 to you, but its obvious its not to kl0wn. What makes a debug kit a debug kit is not the case, or some extra ram, its the whole package, but most importantly the MCPX that was used. The one that kl0wn recieved was definitely a retail mcpx. This was checked by several people with extensive development kit collections, and game developers who use the systems daily. And if kl0wn dropped an xdk recovery cd in that xbox it would be rendered useless, which is certainly not what would happen in a true debug kit.
As for the actual worth, you mentioned selling on ebay, where a mint dvt4 kit just went just barely over 500. I highly doubt a retail mobo, with the tsop flashed and 60$ ram upgrade, in a debug kit case, will fetch that much. If you really feel that it is worth what was paid, you should let kl0wn return what he purchased. IMO, what he got was worth half what he paid.
Your conflicting reports on whether you opened and cleaned and didnt open but checked out the ram just make it all laughable.