Credit Card Solution for WordPress Site?

Anyone operate a wordpress store and know a good solution for accepting credit cards? I’ve looked at a bunch, like PayPal and authorize.net but they all charge upwards of $30 per month on top of activation fee and per transaction fees. The problem is that I don’t expect to make much more than that for a long while so that would make no sense for me.

I’m thinking that there must be a purely per-transaction-fee based thing online, since for physical CC payments there is The Square and Breadcrumbs and all sorts of stuff that have no monthly fees at all and even give you the hardware for free.

So anyone know of any? And I will be using them with a wordpress site.