No idea on the accuracy of this, but this article claims there's a company (http://www.neuvokascorp.com/) making basalt rebar at the same price as steel: http://cleantechnica.com/2014/11/06/neuvokas-basalt-rebar-li...

I am afraid I don't know specifics. For a while the only suppliers were non-American (primarily Russian), so the market prices were not equitably comparable. /r/floathouse (link [1]) will have up to date information.

Interesting. I've made a quick search over Runet, it seems that basalt / basalt-plastic rebar is in large-scale production: http://nano-sk.ru/stekloplastikovaya-armatura/bazaltovaya/

They claim it's better and cheaper than steel rebar. No word about disadvantages, which I assume exist (edit: found, see below).

Edit. Oh, they carry a price: http://nano-sk.ru/price-list/ -- 1m of d=14mm rebar costs ~$0.60. But I don't know the price for the regular steel rebar, though :)

Edit2. There's a list of disadvantages here (sorry, in Russian): http://www.tdbazalt.com/category/materiali_dlia_stroitelstva...

1. Can't stand high temperature, as basalt rebar has polymer as a binder for basalt fiber.

2. Can bend easier than steel; will break easier than steel

3. Can't stand alkaline environment (there're claims that some newer types of the basalt rebar don't carry this issue)