Mike,
We use www.formstack.com for most of our forms. If you do not have a security certificate you can use the forms hosted on their site. Since we have a security certificate we have the form embedded directly on our site.
https://templeemanuel.formstack.com/forms/donation is the version hosted on their site which does not require you to have security certificate.
Since we have an SSL were are able to put the same form on our site. https://www.emanueloftempe.org/giving/donate-to-a-fund-or-campaign
We also have many other forms on our site from Formstack, Religious School Application, Class registration for our Discovering Judaism class, High Holy Day Ticket purchases, Member Fees Payment, Financial Assistance Application, Kol Nidre Pledge/Payment and several for event registrations.
Richard