Target has Finding Nemo Bluray + DVD for only $12.99 this week. It is advertised in the weekly ad and I also double checked in store. This is an excellent deal and no coupons are required.
The sale runs through 12/29 and is available only in stores.
You can check out all the Target deals here.
If you combine this sale with the Kellogg Pixar rebate for $10, you can get the movie for $2.99!