Here are a couple of deals available on DS games right now:
Lego Harry Potter for DS for $9.99 and it ships free
LEGO Harry Potter: Years 5-7 – Nintendo DS for $19.99 and it also includes free shipping.
The Lego Harry Potter for DS Years 1-4 is $14.99 on Amazon right now and the LEGO Harry Potter: Years 5-7 is $29.99.