You may be able to find one on Craigslist.org or oodle.com, they are both free sites where people can resell their used personal belongings.
You can find an inexpensive used treadmill in Houston at www.preownedfitness.com or at http://houston.craigslist.org/spo/.
You can find used treadmills for sale on the auction website Ebay.
There is an old axiom that you get what you pay for. A treadmill with a warranty is unlikely to come cheap, and a cheap treadmill is unlikely to come with a warranty. Your best chance would be to visit a secondhand sporting goods store and then try to negotiate for a warranty. Your only option is to find a treadmill that still has it's orignal warranty left on it. Otherwise there are no companies that specialize in used treadmill warranties.
Ebay has lots of used treadmills for auction or buy it now.
A good quality used treadmill can last a lifetime with proper care.
People do sell used treadmills for good prices at auctions. You should go to Ebay and do a search for "used treadmill". You can often find treadmills for as low as $100.
Check out www.craigslist.org in that area for used treadmills people may be selling for cheap. You can also try www.overstock.com for great deals.
You can get a used treadmill from eBay. There are also a number of used treadmill on Amazon. There are exercise machines for decent prices, depending on what you're looking for in both places.
You can try your local craigslist site or ebay. Of course a treadmill is quite heavy so if you can't pick it up yourself you have to figure in the cost of shipping.
You could find a good used treadmill runner at the following sites ebay.com , or amazon.com . You can also check out sport centers sometimes they sell used equipment at great prices .
The most economical place to find cheap gym equipment is on eBay or craigslist or any other venue to purchase used equipment.
You might be able to pay less for a better brand of treadmill if you consider buying used. If you prefer to buy a new cheap treadmill, go to a store where you can test it out, and read online reviews to see how others feel about the brand you are considering.