Thanks for your feedback. You should add tracking non-respondents to the idea section of the forum so people can vote on it:
Payments has been a frequently asked for feature and something we hope to provide in the near future. You can vote for it here:
FormsCentral now provides the ability to integrate your forms with PayPal. In one seamless experience, respondents can fill out the form and pay using a credit card or PayPal account.
You can read this tutorial on enabling Payment Processing to learn more.
We also have created a dedicated community forum Payments to help better support you.
Please tell us what you think.