I'm working on a SaaS app at the moment and recommend Stripe for payment processing. Stripe is very developer-friendly and has a good reputation.
Regarding the marketing automation side, I would recommend using Intercom.io instead of Infusionsoft. For one, Intercom.io's pricing seems more reasonable and affordable than Infusionsoft's pricing, and Intercom.io is meant specifically for SaaS companies whereas Infusionsoft is not.
If you're looking for a truly all-in-one solution, Intercom.io may also be a better choice because they include a support/ticket system. Assuming you don't need a support solution as large and complicated as Zendesk, Intercom.io may be able to meet all your needs.
You may want to reconsider eliminating your 30-day free trial... Lincoln Murphy from Sixteen Ventures has a great series on pricing strategy for SaaS companies where he addresses free trials and a host of other pricing-related issues. I recommend reading his blog post here and watching the free video series (click the green button that says Pricing Page Success Formula).
By the way, I stumbled across Chefmetrics not too long ago and think it's a brilliant idea! I wish you all the best with that and Bomnipotent, too.