If you're absolutely going to get the 3DS eventually, it makes more sense to buy the 3DS than to buy a DSi now and wait for a price drop. The value of the DSi is likely to drop just as fast as the value of the 3DS, if not faster. So, by the time you're able to get a 3DS for $50 cheaper, you're also getting $50 less from selling your DSi. Might as well buy the 3DS now and enjoy the games that'll come out for it.