Cards that have activation codes on them, when activated you will get CE. Available in Best Buy, Target, 7-Eleven, Shoppers, ETC.
I'm in my early teens. Not old enough for a job, no credit card, can't write checks, not good with this whole mailing thing, and run on a monthly allowance. I'd be more than happy to be a paying customer for OOO but begging my parents to buy me CE isn't going to work out.
I don't think the game is big enough to attract stores like that. They're crossed 1 million accounts, but I think games like Runescape and Gaia have at least 5 million (I'm pretty sure those numbers are too low). But yeah until we hit something like that, I don't think they can sell to stores like that.