It appears to be the only one available, I found three listings, but they're all for the same copy in Galashiels, just in different countries. (It was not a big print run - about 2 or 3,000 copies, I think.)
If you are interested in the Roubieks' work and history, their place, importance and influence in contemporary glass I cannot think of any better book to have.
Well done for nabbing it - I think you will enjoy it. I love mine.