Medical Boot

Does anyone know where I can get a medical boot besides getting one from the doctor. I have to call and make an appointment for my foot tomorrow morning, but I'm pretty sure they won't be able to fit me in anytime this week (or probably month for that matter). Based on how my foot feels and the conversation I had with the podiatrist last year, I'm almost positive he is going to put my ankle in a boot for a while. Why wait? I'd like to start the healing process as soon as possible...now if I could just get one myself..... Thanks!