The yellow Alps went unsold at GH for many months.
The amber Alps you can buy from here: http://www.blujay.com/?page=ad&adid=3138253&cat=0
(which is where I got them)
The rest of the loose Alps switches came from a Mr Interface sample kit.
Yes, I still have a long way to go: Alps SKCL Compact, SKFL and SKFL compact, SKFR/SKFS, the other integrated domes, side dome, the other SKCL/SKCM/SKBL/SKBM (especially the ultra-elusive SKCM Green); Datanetics; M9, ML, and the other MY and MX types; cyan and white Omron; SMK 2nd gen latching; Micro Switch Hall Effect; Apple hairpin spring; and many others.
Still, it's coming along slowly.