I'm not 100% certain on all this, but from memory:
- The Skyline Camouflage models started this year, I think
- Olive Drab and Sand have been available since a long time (possibly since original release, I don't remember) and should still be in production (albeit generally only in SBK versions)
- Green and Purple I believe were among the original colors of Mini Grips, but were discontinued a while back, probably in '05. You might check the Benchmade PDF catalogs that you can download from their site
- The Grey editions, so far as I can remember, were a limited edition run, I think available in the plain/satin and SBK, and possibly the CE/satin blade options. I believe said limited edition runs were in '06, probably 500 or 1000 pieces of each model
So that should give you a rough idea of the histories of these Grip variations, but hopefully someone out there might know more specific dates, if that's what you're looking for. Definitely check the PDF catalog, though, as it will tell you which variations were officially offered for any given year.
