[quote name='Shady Hombre']Why has this game been so consistently cheap (for a first-party DS game)? Not selling much or something?[/QUOTE]
Amazon was really the only retailer that had it marked down for quite some time. As far as I can recall, they've had the game at $25 since practically release. A few other retailers have had deals (like Target having it for $25 near Christmas), but the price goes back up after the week.
I'm not really sure what the deal is with Amazon being able to mark it down so much. They had other games (like Bowser's Inside Story and Mario and Sonic's Winter Games) that were marked down at the same time, but then went back to normal prices (although, both mentioned games are currently $25 again). Typically, first-party Nintendo games take quite a while to drop in price.
Speaking of which, I have noticed that prices on some first-party DS games have steadily been dropping in price over the past few weeks.
Mario Kart, for example, is at $28.54 currently. I consulted the
price tracker to confirm what I've been witnessing: It started at $33.50, dropped a dollar on the 6th, the 11th, the 13th, the 17th, and the 20th. Professor Layton and the Diabolical Box is another that is doing the same thing (dropping about $4.50 in 50 cent to a dollar increments since the 10th), and there are probably others.
My only guesses are that it is because of rumors that Nintendo is going to announce a new handheld at E3 or that they're trying to better compete with their marketplace. If it is the former, it's odd to see them doing this with games which are consistently in their top sellers (Mario Kart, typically being in the top 5).