Simple square aluminium tubing would be cheaper and with similar characteristics for this application. You can assemble them quite easily with a drill and bolts/nuts/washers of the appropriate size.
The advantage these profiles have is that they are more precise, are more easily adjusted and allow for a wide range of connections.
I've done all of my extrusion cuts using my miter saw with just the stock wood blade, I go a bit slow and the cut is basically indistinguishable from the factory cuts. I assume it'd do as well on tube stock, but if I was cutting large diameter solid stock I'd probably go with a non-ferrous blade.
The advantage these profiles have is that they are more precise, are more easily adjusted and allow for a wide range of connections.