MMM or RX8 is unnecessary in the Mini, especially if he's only planning on running 3s. Ezrun 60A or 80A would be good enough for 3s.

These are some cheap options;

http://hobbyking.com/hobbyking/store...dproduct=14635

http://hobbyking.com/hobbyking/store...idproduct=7188

http://hobbyking.com/hobbyking/store...dproduct=11743

http://hobbyking.com/hobbyking/store...idproduct=8993

Or if you think you might want a higher voltage/change the motor later on, this is a relatively cheap investment:

http://hobbyking.com/hobbyking/store...dProduct=10370

These are some of the cheapest options, but not necessarily the best. If you want a product with a warranty, I suggest the Traxxas VXL-3s. It's also waterproof. :P

http://www.amainhobbies.com/product_...rol-Waterproof