The price tag 
Especially because the 3DS is due out sometime soon, and I don't know how much, if at all, the DSi will go down.
Bad times. Still, probably will go down. Although if you wait til the DSi comes out, the trade-in value of your present DS might also go down (if a 'part exchange' route was one you were thinking of taking). Recently, a 'CeX' shop opened near me and I discovered that that they generally appear to put Game/GameStation to shame with their valuations. Got a good price on my DSi, heh.
