If your limited in funds after your new esc/motor purchase and still want a new car then a B4 FT is always a good choice. You can get them really cheap on here now and there still a very good car.
you've also got the added bonus that everyone and his dog has had one a some point so you'll be able to get good reliable setup advice which is something you may be missing with your madrat.
Re radio, then this, in my opinion is you most important bit of kit. Alot of people think I want a car as fast as possible and go all out getting the best esc, motor and cells ect, but then fail to get a decent radio. It's no good having a fast car that you can't control.
I would go for either a KO, Futaba, Sanwa/Airtronic, or Spektrum radio. You can get some good second hand deals and buy the best one you can afford.
By the way what speedo/motor/servo did you get. I'm sure the RC Lazy boys pointed you in the right direction.
