I have to say that I have seen quite a few small melon beads in the Czech Republic, but not these bigger ones like the one on your necklace.
Does it appear to be molded (does it have a seam) or is it a wound bead?

It might be that they were made for a specific purpose and there are not that many around. Could also mean they were not actually made in the Czech Republic.

Anyway, I like the finished necklace.