Those aren't all second hand sofa beds or used sofa beds, most of them are new, and cheap, sofa beds. Those are the best of the listings for discount sofa beds on eBay. eBay is a great place to buy sofa beds cheap, or anything else cheap, and usually brand new.
That's because so many retailers quietly sell many of their products online, on eBay. So if you're in the market for a cheap sofa bed then grab one right here, at Cheap Bedroom Furniture