I currently have an iphone, but that's probably to fancy for what your wanting it for. Prior to this one I've had a Sharp and a Nokia. I think Nokia's are the best, very sturdy. I know I've dropped my old nokia from my front landing onto concrete and it's survived.

The memory card shouldn't make any difference to why your phone is constantly losing power, that sounds more like a faulty battery. Ask the shop people to test the battery if they can and see if tat's the problem.

Good luck!