J.G. Pasterjak's DIY ladder dolly a.k.a Cinemover is a solid little track dolly. The adjustable width makes it easy to find a variety of different tracks from straight lumber, square tubing, or round rods. Using heavy duty steel perforated square tubing as the chassis and skate wheels / bearings makes for a smooth ride. [Thanks J.G.] Still a hand made DIY (not mass produced), so quantities are limited, and you can check out details if you want to make one yourself. If you're not into building or buying, maybe winning a contest might be up your alley. There's a few RTG (ready to go) versions and other information available on the eBay listing following the link (click here).
Future mods on the J.G. Pasterjak's DIY ladder type dolly make it much more functional than before. The new materials used to assemble the dolly allows for it to be used on flat surfaces (when flipped upside down), or on a variety of track widths. The ladder dolly design allows you to use almost anything for tracks such as two conduit pipes, two square tubes, or even one solid wooden plank (as seen in the video). Personally I really like this design, as it's still a DIY, but has a much more professional look to the build. The extra heavy bars probably add more stability to the rig too. J.G. Pasterjak mentioned that these units might soon be available on the big auction website, so stay tuned for that. [Thanks J.G. Keep us posted on those units]