It is both in Origin and Steam, as well as on Amazon as a digital edition. You can also get it some other sites if you just do your googling
EDIT: It is on Steam but it seems to be locked for some regions
http://store.steampowered.com/app/24860/As far as Origin goes, I have it on there so I know it should be in the store, but it isn't. Again, your best bets are Amazon or a trusted reseller that has a code/gift you can purchase.