yes they are worth the $135, I can almost gurantee you'll pay more then that even if you build them yourself. IF you want a bolt on option why dont you get some 1/8" flat bar, drill a few holes and bolt it up. Just weld the tubing to the plates. You can also do a "C channel" design where 1 bolt holds pressure against the frame.
When I did my own sliders on my 88' I just welded them to the frame and had no trouble, they were very sturdy and took a hard beating without any breakage. If your not a welder things to look for is a weld that has good penetration into the metal and looks consistant. Imagine a stack of quarters that fell over and are stacked along one another, thats what a weld should look like.
