Right now you can buy $10 worth of credit at Dealpulp for just $1. DealPulp is a daily deal site that is just getting started. they also offer a free $5 credit when you sign up using someone else’s referral link. (Here is mine). So, if you are not a member yet you could, sign up through this referral link. and then buy a $10 credit for $1 and for $1 you would have $16 worth of credits.
I’ll be honest, I am kinda lukewarm about this site and deal. They did offer a $7 Target gift card for $10. But I have not seen very many other good deals yet.