I asked an employee at GameStop about the DSi trade in deal, and she said that you can trade in more than one and still get that additional equal amount for your trade (has to be towards a 3DS of course). I can get DS Lites pretty cheap (broken, that I can fix), so I can potentially get a super cheap (if not free) 3DS if I get working. So far I have a DSi ($75), I can probably get 2 or 3 DS Lites ($50 each) and be well on my way by 2/20/11 (when the deal ends).