Try a used treadmill before you buy! Try it again before the buy! Think again, list all the negative points, why you should not buy this particular treadmill, and then finally decide whether to buy it or not!
Before that, are you psychologically ready to buy a second hand product- the one used by others? This issue is very important. Hundreds of people are going to ask you this in the future, why you bought this secondhand treadmill. Every time, you need to give them a sort of mini-discourse and convince them, as to what made you go for a used treadmill purchase! If you have made the buy against the wishes of your wife, she is not going to pardon you for lifetime! Take it as a guarantee!
There is, however a difference between a used treadmill and the refurbished treadmill. By buying a refurbished treadmill, you have actually bought a new treadmill. In the process, you have saved thousands of dollars as well. But you need to know the art of buying a used treadmill, and you need to take some basic, unfailing precautions.
By buying a used treadmill, you have already saved the gym fees. Perhaps a few months fees would equal the cost of the treadmill you have...