A couple thoughts on the main topic of this thread:
First, I suspect that maintaining a so-called "good stock" of bees with a relatively limited number of hives would be very difficult if not impossible, short of using instrument insemination (II) extensively.
Using II, I believe you could maintain lines for breeding purposes much more effectively, especially with a limited number of hives. Without relying on II, any queens would be open mated, and open mating would leave you at the mercy of fortune or luck or whatever you wish to call it, in terms of genetics.
Secondly, I wonder how much real difference lies between the stock of any two breeders at this point. (I'm sure, after typing it and thinking about what I just typed, that any number of beekeepers will jump in here and describe examples of "good stock" and "poor stock," but I'll run with it for now.) See, if queen producer Adam has queens of line "Excella" and queen producer Zane has queens of line "Shoddy" and the two produce queens from apiaries located two miles apart, the queens are likely mating with drones from the same pool of available drones. Since the workers will get 1/2 of their genes from the drones, any resulting "stock" may differ less than the original "Excella" and "Shoddy" lines differ from one another, and any subsequent queens will only have 1/2 the genes of the original lines.
Like others have suggested, if you intend to produce (hypothetically) Carniolan queens, and some of your neighbors are migratory beekeepers, those Carniolan genes are likely to get watered down by Italian (or whatever stock the migratory 'keepers are using) pretty quickly.