Baja Buggy

i wanna build a cheap baja buggy. but i dont know how much one would cost. what i want to do is beef the engine up a bit, add a roll cage, put a lift on, and put baja rims and tires on. on top of the cost of the car and the cost to repair it. my thought on the price is about 4000-5000$. anybody konw a good estimate?