Sinamex also carries Elixirs but you'll get better prices with Brendon. Furthermore, he'll send them to you through the mail so it's a lot more convenient for you, too.
For electric, you might also want to try the Everly strings Brendon also brings in. They're uncoated, but they last quite long and they still have the best feel I've tried to date. Really nice strings. I didn't regret spending $11 on them (not to mention getting a V-pick at a very much discounted price at the same time).
does brandon carry 12 string packs?
no idea, maybe you should drop him a PM (;
his soft username is brendon