Pro purchase link giving HTTPS error

When I click the link to purchase, I'm getting the following error:

There is a problem with this website's security certificate.

The security certificate presented by this website was not issued by a trusted certificate authority.

Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server.
We recommend that you close this webpage and do not continue to this website.

Thanks! Will immediately report this to avangate.

This has now been resolved.