The use of a R/C transmitter to control a robot could give the wrong impression in demonstrations and make the audience think that your robot is nothing more a glorified R/C car than it is a robot(it is an R/C car if you are using this control method).
Although expensive the VEX Cortex, is used by quite a few teams as a Robo-rio replacement. It will simplify your demonstrations as no driver station is necessary, but it still allows a great range of functionality and is similiar to program as a normal frc control system, making it a good learning opportunity for programmers.
http://www.vexrobotics.com/276-1604.html
Couple the VEX Cortex with a few low cost PWM motor controllers like Sparks or Victor SP's or old Victor 884/888's, Talon SR's and Jaguars with a basic power distribution board ( could be from an old control system or just a small fuse board, depending on how many motors you plan to run) a circuit breaker and a SLA battery and you have a relatively low cost control system, which allows you to utilise as many existing parts as possible while making demonstrating the robot simple and professional