I really want to use Stripe but it would be great if they had a more favorable pricing structure for microtransactions. Paypal, for example, will charge 5%+$0.05 or 2.9%+$0.30 (whichever is lowest) for digital goods transactions.
It mightn't suit your use case though.
The workarounds with bundling transactions don't really work for my use case.
I'm pretty sure the OP was referring to credit/debit transactions...
I think Knox with a fallback to Amazon Payments is a great stack for Micro if you want my opinion.