You would have to mod it with a brushless system to get it up to those speeds. which would run him a little more than $200 total but I dont know of any RCs that will go 40-45mph for $200 or less.
Some of the brushed Traxxas kits will do about 30-35mph and I think like the Rustler comes in under $200. Take a look at THESE. Any one of these (maybe not the bandit? lol) would be a good starter kit. Theyre gonna be a little slower than what you are hoping for but can be made faster later on and they will be a lot bigger than the Losi Mini-T. Not that theres anything wrong with the Mini-T, I have one of them and a Mini-B but I'm guessing you're looking for something bigger.