Something I don't think has been mentioned in this entire thread: It is probably in the contract they sign. Even if the kit was free, I am certain they sign a non-disclosure agreement. And I suspect if they don't use the kit, they have to give it back. Nintendo is not about to let the kits float around, not at this point in the game. I saw the one offered on ebay, I am sure that 1. it will be pulled before the auction completes and 2. Nintendo will be tracing its serial numbers. Remember Nintendo knows where EACH of those kits go and have a legal recourse if they so choose. And for a console that is not even a year old, you can bet they are going to choose to protect it any way they can.
Also keep in mind after singing a non-disclosure agreement, I certainly wouldn't want to take the risk of this tech falling into someone else's hands and have Nintendo come after me, if I wasn't using it anyway. Much easier just to say "here take this back, I don't want to take responsibility for having this". And even if it is not in the agreement, again it is simply not worth keeping and possibly loosing track of it. Then have the kit show up on ebay and Nintendo's lawyers on your doorstep.
Also keep in mind after singing a non-disclosure agreement, I certainly wouldn't want to take the risk of this tech falling into someone else's hands and have Nintendo come after me, if I wasn't using it anyway. Much easier just to say "here take this back, I don't want to take responsibility for having this". And even if it is not in the agreement, again it is simply not worth keeping and possibly loosing track of it. Then have the kit show up on ebay and Nintendo's lawyers on your doorstep.