"You probably wont find a wireless device that is capable of 400 feet for 20 bucks."
Not $20, but I stumbled across an impressive product that provides enterprise class gear at a bargain price. It is Ubitiqui (ubiquiti.com) and they offer an outdoor access point that touts 300M speeds up to 600'. They also offer point-to-point systems to extend internet service for many miles, assuming you can get clear line of sight, comes in 2.4MHZ and 5MHZ.
All the usual disclaimers, found them while trying to get broadband service to my new property.
