I would recommend any of the ECX lineup. I did a full review of their Boost buggy a while back and I was very pleased for the price. I will also post a link below to an article I wrote explaining different kinds of transmitters. Let me know if these help.
-Boost review: http://www.modelkits.com/radio-contr...rc-review.html
-ECX's website: http://www.ecxrc.com/
-Article over transmitters: http://www.modelkits.com/radio-contr...nsmitters.html
-Even more in depth over transmitters: http://www.modelkits.com/radio-contr...s-operate.html