Well, initially, the cost doesn't really matter - its a funded research project that develops the technical end of things. Once the material is understood, then the means of getting it into the construction industry/culture is next - usually through other gov't funded sponsorships and then hopefully, the thing takes off with a life of its own and the price starts coming down as more and more suppliers have it, and can produce it economically.
The material may cost more, but the number and size of beams may come down, along with lower cranes needed and lighter trucking to the site. Also, lower footings. I would think all these would need time to develop and if it doesn't end up being competitive with current methods, it goes away.