If you're on Verizon, you can't buy a used spare phone on Craig's List for that little, so yes. Just keep the battery charged and if your main phone ever breaks or has to go into the shop (or if you're going to be in a situation where your phone might get broken, wet or stolen), switch to that one. (If I were on Verizon, I'd run out now and buy 2, just to have a spare spare.)