Here is one we just got that is not too expensive:
http://www.spinlife.com/critpath/spe...roductID=74112
Advantages:
Not too expensive
Can be taken apart and placed in a car
Can be shipped to your door
Disadvantages
Not good for outdoor use
Not real rugged
Not much seat adjustment - it either works for you or dosen't
No warranty or other maintenance except at your cost
There may be other options for you at the site.
Kent