Most everyone who's lipstick crazy may already know about this site, but some may not. If your favorite lipstick has been discontinued and you still have a little left, you can send it to them (they'll return it) to analyze, match and blend for you. If you don't have any left but have the name, they may already have it in their database. A little expensive perhaps. I haven't used them yet.
or, if you want to skip the intro...
I have also read that Prescriptives will now custom blend lipsticks and glosses for you.