Creating a short simple animation film to explain a product

I am looking for someone who can make Simple animation film, 2-5min, include voice explanation [I will give the 'Story board'] .
More or less like one of the following examples:

dropbox : https://www.dropbox.com/
or
http://www.youtube.com/watch?v=4P785j15Tzk&list=FLo9w9ShV8T0u2r5W3FsBpnw&index=14&feature=plpp_video
or
http://startup-videos.com/kactoos/

If you think you can, please send me an example for simular things you did.

A short list of the information you need and price estimation more or less.

Thanks

Einat