hey cookiemonster,
If you haven't already, check out this blog post: http://www.theforge.co.za/2012/06/13/south-african-payment-gateways-that-dont-require-bank-registration/ - very helpful. Download the pdf guide for a full breakdown of payment gateways that require merchant registration and those that don't.
My problem now is that I don't think any of these service providers can plug in to the theme that I'm using, but hopefully I'm missing something.