...we don't know where you reside/need to use your phone. Coverage is king, so w/o such info, how could we possible know which carrier works in your location??

Essentially, the large carriers are not the best choice if you need lower prices for service. But if you required faster data speeds, it may be the better option for you. YMMV. You will not however be able to use your cousins 4S on ATT's network w/o a data plan.

I would research the various prepaid plans to get the most bang for your buck if all you do is call/text.