Two different, used walkers are available, as pictured. Both are height-adjustable. Different levels of prior use. See below descriptions.
The first walker is an Invacare model that has walker skis on the back legs. $30
The second walker is a Medline model that has walker skis on the back legs, which makes them much easier to glide over surfaces (and much better than tennis balls), and this one hasn't been used very much. $35
I also have some extra, used walker parts: 2 small wheel replacements, 2 stationery legs (no wheels), and 2 gray rubber tips. $17 for all of these extra items (as a lot).