I believe Disgaea is only $19.99 at target. I got mine there months ago. Plus I just saw a few more copies there just the other night that they got in.
Target is a planned-space environment. While it makes for really nice, neat display cases (as opposed to say, Kmart or some Wal-Marts with haphazard stacks of games), it also means that once a game falls below a certain sell-through amount, it will be rapidly marked down until gone to make room for a game that will sell better. Then wash, rinse, repeat. That's what happened to Disgaea, and I would be surprised if there were more than a handful of copies left in the whole chain, because once that mark-down process happens, they're not bringing the title back in. It does make for some killer deals though, if you time your visit just right.