Ebay bag kits?

[Dkayfes44]

I'm new to this forum and appreciate everyone who shares all their knowledge. So I have a 72 gmc k15 that is currently on the operating table getting air bagged. I've been doing alot of reading and have decided to go with 2600 bags all the way around. Triangulated 4 link out back with bag on bar and step notch. Going with 2.5 drop spindles and cupped lca on the front. Trying to keep everything kinda simply as this is my first time doing a full bag suspension. I've been looking at these kits on ebay that are selling for around 500 and claim they have almost everything I need, bags, tank, compressor, switches, plates. This seems to good to be true by the fact that 4 dominator 2600 go for about 300 alone. Anyone have ANY experience with these kits? Are they a total waste of time? My original plan was to just buy 4 bags and make my own plumbing and delivery system but even doing that I'd have more than 500 into it. Thanks in advance