Jay, the Uniclamps are nice, but they are pretty much "dressed up" F clamps. They do not have the true parallel design that the K-Body and similar clamps have. I have a few of the Uniclamps and like them, but they are much lighter duty than the parallel clamps from Bessey, Jet, Jorgenson, etc.
Your point about the kits is a good one. A good quantity of my K-Body stable was build using the kits with 24" and 40" clamps when they went on sale from time to time. I would really like to get some of the 12" K-Bodies as there have been a number of times I would have liked the extra "oomph" they provide without a long piece of metal bar sticking out and waiting to crack my skull open. Unfortunately, the 12" version has never gone on sale at an "attractive" price that I've seen. Even with the close-out on the current design, I haven't seen any real movement on the 12" price...so far.
--
The most expensive tool is the one you buy "cheaply" and often...