I think you mean offset material cost? 2 fold answer; faster, and less concrete since shell is thinner by quite a bit. RE; labor; this is heresay, as I haven't done it. I talked with people who have. 1) sizes up to 12mm come in 300 ft rolls that can be carried by 1 person. For a 50 ft dome, the arc is about 78 ft. For steel rebar, that's 4 pieces 20 ft long tied together, then has to be bent to form the circle. For basalt rebar, measure it out in 1 piece, cut off at correct length with power tool/diamond blade. Put 1 end in hole in concrete. Walk to other end, pick it up, walk to hole on opposite side of first. The basalt bends like a stiff pole vault rod. You need someone to keep it in the right place while you get a second piece up. Each should be marked in the middle where they cross at right angles. This is 25 ft in the air, so you need scaffolding or a cherry-picker. Once three or four pieces are up and tied off, it is self standing. The horizontal pieces are even easier; they can go up in a spiral, no cuts needed. I haven;t verified this with an independent engineer, but the basalt company engineer claims it works. All this saves a lot of time, but the cost of concrete savings may be more important.
Unskilled laborers put up 20 to 30 foot domes in 3rd world countries with no problem. 40 and 50 foot domes represent a bigger risk if inflation fails, or someone falls. But the basic steps are still much the same. There are pamphlets on this website that show the basic steps for smaller domes. Do the research yourself, you will be more certain of the facts that way. There are videos of owner-builders doing large domes on You-tube if you search. It can be much easier with basalt, and the trade offs become apparent with research.