I like https://www.dwolla.com

There is a big barrier to getting people to sign up, but a $1 transaction has NO FEE.

I used it for paying a contractor instead of paypal or a check and for that it cost $.25 for a payment of $5k.

I don't think there is one. Perhaps another way to look at it -are you really only adding $1 of value?

You could also look at a form of prepay, clock in 20$ credit only use $1 worth

I use Authorize.net and pay 2.75% + $0.10.