If you want a Corvette you would buy a Corvette right? If you want to win races you would buy a car that has proven itself over and over again right? 1/8 buggy's are not going to ever be a cheap car to run so trying to be cheap about it is foolish. The cars are expensive and so are engines and tires. If you want to be a cheap ass get a mini-t or something.
If you want to win races buy a KYOSHO! or mugen.