Get standard size ball bearing servos from a reputable company. Hitec is good, and I'd do HS-435BB servos all around. They are a little stronger that you need, but they aren't expensive and they'll also be strong enough to use on future planes. Futaba 3004 servos are another good alternative.

And, as a general rule, I'm going to advise against buying anything mainly based on it being a good deal. Sure, if a reputable company is selling a well proven product at a discounted price as part of a promotion they are doing, snatch it up. But many good airplanes have been crashed or lost because a new pilot decided it was super important to try and save $20 on servos or a battery or by buying a cheap radio. Buy good things and take care of them, and you'll save a whole lot more money in the long run.