Not buying one. Ever. Not only do I still feel that Nintendo loyalists are being taken advantage of through their unwillingness to to reject the "innovation" lie, but there are no games that warrant a purchase of a new system for me. My three criteria have not yet been met for even considering the purchase of one, those being: a.) A new Legend of Zelda game is in the works with video and screenshots available, b.) Pokémon Diamond and Pearl are proven to be the legitimate heirs to the series, and c.) A new Fire Emblem is in the works with video and screenshots available. Only a.) has been met as of yet, but it may be permanently cancelled if Phantom Hourglass has a Majora's Mask-esque time-based system.
This is not even including the factor that I will refuse to buy a system on principle if I see something inherently wrong or dishonest in the system, hence my refusal to buy such systems as the DS, Xbox, Wii (*twitch*), and others for various reasons regarding company philosophy behind the existence of the system. If you care that all you're doing is stroking Nintendo's ego by purchasing a DS, you may want to think twice, but if you don't care....there's really nothing I can say or do to stop you.