Look around at the vintage tripods on ebay too. I don't know what kind of Craigslist scene you have up by you, but they are always worth a gander too. (Find a sweet old Quick-set or something dirt cheap and absurdly heavy duty.)
The surface dolly is just to mount the camera right to. The table top dolly with the mini jib (in one of the other threads) is cool for small scale.
You could also just build your jib on a flat based stand that sits on your dolly.
I keep an eye out for flat roof antenna mounts. You screw it to a piece of wood, then it has u-Bolts for a pipe, and done.
Here is a flat base with a part from a kitchen table I found:
(I made a dolly from the whole table top. (It was round and had fold down(up) sides. We used to call it the Bat Dolly.
)
I made (Pictured below) "Drop-in quick mount" for a tripod or jib ON a little doorway dolly. It worked really well. (It's just a piece of beam (bolted to the dolly and dolly lip) that had a pipe flange bolted to it, and the pipe had a few supports that bolted to the dolly truck bolts. (Most of the connections were all threaded, so it was rock solid.
This one is just to make you laugh. (A knife block and some garage door rollers and some conduit track.):
-Thanks-