Cathi,
Tripods are not that expensive to build, and the material is readily
available, usually four inch heavy pipe, 6 to 8 foot long, with
prongs/skid plates. And any place that builds or erects grain silo's
has the basic thing you need.
Most on here have made or acquired their's rather cheaply. I recall
seeing them in a catalog upwards to $800 and not built very well. I
think it would be best if you designed and had someone at a welding
shop do the rest, even to the point of taking an ad out in the paper.
There are tons of people who have the skills to build one.
I have been working on a two wheeled scheme that you pull behind your
car on a ball hitch. It would have four "legs" attached to a frame with
four drop down
"supports", and the frame would open at the rear so you could slide it
into the area.
The key here is mobility and safety. A third tire that swiveled in any
direction would help move it by hand, and a hand brake for that. Having
had a tripod "crash" on me more than once, I suggest never doing it
alone or without gloves and a hard hat.
Lee Creed