I've got the whole thing I picked up slightly used for cheap, but all you really need are two sets of pins and the prepunched carrier sheets. Design a layout board yourself, mount the pins on the board (take a carrier sheet, cut the top edge with the holes, place the pins in the holes, and tape it to the top edge of your layout board. Do the same with the other end of the carrier sheet you just cut one end off of and mount it to the glass of your exposure unit in an appropriate spot).
You could also buy a punch and 2 sets of pins from an offset printer supply house and punch your own mylar, but the punches are not cheap. The pins and carrier sheets from Vastex aren't that expensive, and you reuse the carrier sheets. I've got the grubby ones I got with the used system, plus another box of new ones I bought from Vastex, and I just try and keep the tape residue off 'em. They'll pretty much last forever.
One other thing. The system comes with a jig that fits to your platen, that's aligned with your screen clamp in the printhead (I'm not sure this system would work very well with side clamps). You then slide your screens up against the stops on the jig at the clamp and at the left side, then tighten the clamp to your frame. This is what brings the screens into close registration. This is really the only part of the system that makes buying it from Vastex worthwhile, and I'm not sure how well it works with all makes of presses. It works great with my Vastex, but of course, that's what it was primarily designed for. It is something that could also be cobbled up pretty easily to custom fit your press if you're handy with tools.
I think the real advantage to these pin registration systems (whether Vastex or anyone else's, or ANY series of procedures, is the "system" part. If you can develop a system or series of steps for prepress, and follow it every time, you'll eliminate a certain amount of variables and subsequently reduce mistakes, or make troubleshooting problems easier, thereby saving time overall.