A copy of Rhapsody, used, like I'd planned.
For the person I was with, using my vast knowledge of DS titles to navigate the used-and-boxless section:
A copy of Spectrobes, because he thought digging up alien fossils to make monsters sounded cool.
A copy of Izuna: Legend of the Unemployed Ninja, because it's a roguelike known for being difficult. He's enjoying it, although he points out it's still much easier than Nethack.
I completely forgot to look for Devil Survivor. They did not have any copies of The Dark Spire. They did have Knights in the Nightmare and my shopping partner may go for that next time.
They had a wide range of pink stuff as well but, again, with no ability to play demos I'm *not* going to pick up something like Princess In Lovewhich is probably AWFUL. :) (That 'Sarah and the Unicorn' game was present but I still couldn't tell much from the box.)
Also obtained NOT on that shopping trip: Peggle Nights, because I am still addicted to bouncing balls.