Thanks rando,
I went to the websites: 80/20 seems to have the tubes but not the connectors; ESTO has similar to what I am looking for and had pricing similar to Australian; Kipp also has product, but I could not find pricing. Maybe you could give me more of the others.
As to my usage, I was looking at using them for cabinets similar to modular cabinet kits I have seen for race car and horse trailers. However, my build has nothing that falls into the category of modular. Obviously these connectors work great in compression, but have no value in tension. Connect-It uses a setting tool to "dimple" the tube into their connector, not great for tension, but maybe effective for vibration separation.
I estimate that a 1/2" Birch plywood cabinet frame would weigh about 50lbs (without doors and top) where an aluminum frame about 10lbs. I would have two of these cabinets so 80lbs saved.
I have to admit that I have not looked at the 80/20 system. Their T-slot extrusions and connectors just look expensive and overkill for my application.
Boonie