I had that problem before. The leakage is only prominent when the radiator gets hotter and reving it at the same time. I had the radiator changed myself.

For your case, you should do a pressure test like what mattc said. Change a new radiator if the coolant lines is broken or burst.

You can try going to the wreckers to get another radiator at about 50-80 bucks. A new one might cost you about 120-150 bucks. You can try searching for ppl selling here as well!