I do use StartSSL but the problem just comes from having multiple sub domains. I get IPv4 addresses for $0.50/mo/each but I'd rather not setup each subdomain on its own dedicated IP for the sakes of using free SSL certs.
You don't need multiple IPv4 addresses to make use of a wild-card (or other multi-name) certificate. A wildcard certificate will verify any matching domain so you could have many sub-domains of the same domain (using a single certificate for *.domain.tld) on one address and browsers would not complain.
Also you could run the distinct (sub)domains on different ports on the same address, though this is perhaps less useful.
Also, with SNI you can use many single-name certificates on one address (and all on the same port) using SNI. Unfortunately there are a number of significant client combinations that won't play nice with this (most notably, if you can't guess, IE on Windows XP): http://en.wikipedia.org/wiki/Server_Name_Indication#Support
I know that. I'm saying I don't want to have to pay for a wildcard certificate since you can get free certs for individual domains. The alternative for me purchasing a wildcard domain would be to get many different single domain certs for free and assign each one to a different IP address.
Also you could run the distinct (sub)domains on different ports on the same address, though this is perhaps less useful.
Also, with SNI you can use many single-name certificates on one address (and all on the same port) using SNI. Unfortunately there are a number of significant client combinations that won't play nice with this (most notably, if you can't guess, IE on Windows XP): http://en.wikipedia.org/wiki/Server_Name_Indication#Support