Tim,
The MP ones, if the least expensive, work well and get the job done. Some of the stuff on the market is STUPID expensive for what it does. If you want to fab up something that provides stress relief from the other crap in the world, that's valuable too. My old "pick your parts, pay your money" statement.
Last set I built had about $15-20 in materials.
The biggest issue with the bolt in stuff is the holes will wallow out over time from stresses applied. If you can reinforce the rails where the connectos attach, that would be helpful. If you are alowed to weld them in, that's the best approach.
Rob
