One of the main reasons to avoid buying a used treadmill is it probably is not covered with a warranty.  If you have a service issue, which is more likely than buying a new treadmill, it can be very costly.  In some cases more than the cost of the used model.

 Like an appliance repair call, there is a cost just to have someone come out and look at the machine.  Once they figure out the problem, they'll probably need to order parts, and then return a second time.  You are lucky if you get away for less than $200. 

The only time to consider a used treadmill is when it has hardly been used and is seriously discounted.    There are some brands that will transfer the warranty, if it is still in effect.  If you buy a cheap used treadmill you are asking for trouble, particularly if it has been used on a regular basis. 

Be cautious buying a used  treadmill online at places like eBay.  There are some scam artist that claim to have a treadmill for sale, but will try to get you to wire money first, before delivery.  Don't ever wire money, unless you like to be had.  There was a scammer in East Europe selling on eBay.  She claimed to have bought an allotment of closeout treadmills from a company I use to work for.  We never sold any closeout models anywhere.  She was trying to get customers to wire money, rather than use credit cards.  With some effort I had her shutdown. 

If you can afford it buy a new model with a full warranty.   Click here to see treadmill reviews on popular models.

If you buy a used treadmill, make sure it is a super bargain, and has hardly been used.

Fred