I also went to the vendor market at this year's International Mr. Leather. It's hilarious that you looked there for a crystal-studded ballgag! But, as they say, the journey is half the fun!

And as far as the vacuum cube goes, I have not personally tried it, but I found this writeup of someone who did, as well as one of a few BDSM sites that sells vac cubes. I imagine it goes along with mummification/encasement fetishes, as well as latex fetishes.