Great! Yeah, community would be ideal but a small company like yours is definitely wonderful, as well. As long as it's open source, it's fine by me.
I see you're building on PGP, which has been historically confusing for non-tech folks, but I look forward to see what you've come up with to counter that confusion.
A couple of issues:
1. Not sure if you'll be using the same server/TLS cert for your actual web-based e-mail sender, but I got a giant warning on Android (Kindle Fire running Chrome for Android) about the certificate being invalid. It's probably the fact that you need to host the intermediate certificates on your site (i.e., the chain of trust is "broken"). If you are hosting them, then it might be this issue:
http://www.unrelatedshit.com/2011/10/21/positivessl-not-work...
2. Again on the https, have you considered upgrading to TLS 1.1, or 1.2? You'd be able to offer ECDHE for forward secrecy, among other advantages. But you may have reasons for sticking with 1.0.
3. Are you vulnerable to SSL stripping attacks, like Moxie Marlinspike proposed? You are redirecting http requests to https.
Again, you may not be using this server for your actual registration, but just fyi.
One more suggestion: you may want to simplify the pricing. Do you really need 6 different categories? I'd try to eliminate at least 1, and ideally 2 or 3. Three categories may be the sweet spot (I think there's actual empirical research underlying this, but don't have time to search for citations). For a (non-scientific) summary of this, see:
http://thinktraffic.net/most-common-pricing-mistake
Good luck, and feel free to e-mail me at my username @ gmail if you need a beta tester.