Not sure if this is a one day sale or price drop, but it's $10 on Gamestop.com. I ordered it online, paid the shipping instead of going to the store.
Called my closest store earlier today and he said that yes they were $9.99 at the stores as well so he put one on hold for me. When I went to get it tonight he said "glad you put it on hold." Apparently word got out and the MK Vita scalpers are cleaning the Gamestops out! Mine was the only one they had left!