Any online payment method you like.
Like eBay GCs purchased at Kroger during 4x fuel points offer. I always have a stack of those, Amazon, Home Depot, iTunes, Target, etc. cards.
Even if there is no Kroger around you, get them on vacation if the timing works. I know a guy who pays $6 per 1000 (~4% on top of whatever your CC gets you) and will buy virtual unlimited quantities by Paypal.