[Gundamx92000]

There are PLENTY of laptops under $400, after all there are a plethora of EEE PCs and other netbooks around the $300 mark, sometimes they go on huge sales too. Plus since they're all running Atom boards they all have pretty much the same specs. If you were to add a laptop to the robot, a netbook may be a good choice as they're already made to be small and lightweight, and the ones with solid state drive are already shock resistant. Here is a link to a list on Newegg for reference:

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100006746%204018&IsN odeId=1&name=$200%20-%20$300