Earlier this year JuicedLink showed off an inexpensive roller bearing prototype slider design at NAB2011 with Olivia. Here's another video showing a bit more information. Sold with just a trollery and rail clamps, you'll be able to assemble your own slider at any length you choose. For longer runs another trolley block with roller bearings on each side keep the rails in position. The whole design is focused on keeping the costs down as much as possible. No word yet on pricing and availability, but other information can be found over at the JuicedLink blog.