I paid 400 for mine two years ago. I bought it for one day I hoped to find the elusive 9mm barrel for it.
I paid about $300 for mine, shipped. I've regretted later trading that gun away. At the time I just found that I didn't like .40, but now have no problems with it, and have a number of .40 handguns (including one with 9mm conversion barrels, and a .45 GAP (Glock 37) with a .40 conversion barrel. Seems like a nice option should .45 GAP ever get hard to find.
While most of the 40B is very similar to the standard 75B, you can't swap barrels, as the 40B uses a different lockup design -- no barrel lugs on top of the barrel -- with the barrel locking up in a SIG-like manner. Some of the newer CZs take a similar approach.
Bar-Sto offered 9mm and 40>9m conversion barrels for .40 CZs many years ago, but I'm not sure they ever offered one for the 40B. They soon discontinued their standard 75B offerings -- apparently underwhelmed by the demand. (The .40 CZ was more popular in IPSC, and the guns most widely used there are a larger design.) Back then there simply wasn't much demand for CZ-related products.
If Bar-Sto were to try again for standard CZ models, they might be pleasantly surprised, now that CZ has a following, but back in the late '90s and early '00s, the guns were unknown or novelties.
I'm surprised that other barrel makers haven't offered more for CZs. (EFK Firedragon offers barrels for the FNH handguns, and I'm sure there are MORE CZs out there than FNX, FNS, and FNP handguns.)