i just had a look at openbeam. holy crap that is expensive... their startkit goes for 140$ and got about 7 meters of open beam in it... what happened to the 10$ a meter price ? also their mounting brackets are simple plastic. for that price thousld be a bit sturdier and made from cast aluminum.
There are 8 meters of pre-cut open beam in various lengths in the starter kit, along with a number of brackets, screws, nuts and a driver.
You can also buy packs of six one meter lengths for $59 with amazon prime shipping.
The brackets are glass reinforced plastic and quite sturdy. If your structure is otherwise sound I don't see why they'd be a problem.