In California. I also have a pretty good collection of boxed Japanese/Australian/UK Game Boy Pockets too. I'm missing a few that I'm not holding my breath to find until I go back to Japan again to hunt for them.
I'd love to find a CIB Blue Seibu Lions, Toyota Clear, Glico Clear, and the Nintendo Power 100 Gold pocket. Those ones are probably some of the most elusive colors to find.