APEX

This may be off-topic for Apex proper, but I would like to draw on the experiences of this forum.

I've prototyped a SaaS (software as a service) application in Apex... all is working well and I have a hosting company I'm OK with using.

But now I need to integrate with a recurring billing system (so I can get paid :-)

I really want to avoid PCI compliance issues.

I'm leaning towards Chargify ( http://chargify.com/how-it-works/ ) because of the simplicity, but it needs a payment gateway to push the transactions thru (not a big problem, just another distraction).

Has anyone used Chargify?

Does anyone have a recommended solution to recurring billing for a SaaS application?

I'm also hoping this will fire up a conversation on how we can use Apex for small cost effective SaaS applications. I think I have been guilty of "thinking big" when it comes to designing and building applications, but I now think a market exists for simple but elegant apps that are useful and affordable for the mom-and-pop businesses around the world (think "so easy, a caveman could do it"... :-)

What do ya'll think?

Thanks,
Russ