Hard to find under $20 new
$16 studica
http://www.studica.com/us/en/SonyPlayStation/ps-vita-smart-as/22005_1.html
$17 kmart
http://www.kmart.com/sony-ps-vita-smart-as/p-018V005538858001P?prdNo=11
$10(used) Gamestop
http://www.gamestop.com/ps-vita/games/smart-as/102085
$16 studica
http://www.studica.com/us/en/SonyPlayStation/ps-vita-smart-as/22005_1.html
$17 kmart
http://www.kmart.com/sony-ps-vita-smart-as/p-018V005538858001P?prdNo=11
$10(used) Gamestop
http://www.gamestop.com/ps-vita/games/smart-as/102085