Forum OpenACS Q&A: Advice on where to get an SSL certificate
checkout http://freessl.com/. No frills, fully automated and rock bottom price.
Weve used SureSSL http://www.suressl.com/whichssl.asp prices start from $49.99
The price is $25 a year, I think, but even cooler is the fact that you can get a 30-day trial that works exactly the same as the regular cert. I got one for test.domain.com, which I was happy with what was happening there I got one for www.domain.com, and in two more weeks I'll go back and get one for a year. It looks like you could probably get an endless string of 30-day trials if you wanted to do the work.