2001 Hyundai Sonata continous dead battery

I bought a hyundai sonota-3 days later it started shaking and the battery just died. It was jumped and driven but did not make it more than a 1/2 mile before dying again-the battery cables were replaced and it's been fine for 2 weeks and started this again but this time the lights went somewhat dim and the car died. I try to restart it but I just hear the clicking of the starter-I just bought this car for 2600 dollars for my son and it's already a big headache-can you help me?