https://www.rapidsslonline.com/ less than $20/year, takes literally 15 minutes from start to having a certificate. Well, maybe 30 minutes the first time when you need to read everything.
There are probably dozens of other sites offering similar services; I've used this one several times.
Namecheap reseller: $5/year
I ended up buying one from rapidsslonline, after I learned they require authorization from only the subdomain, not the top-level. I'll check out cheapssls.com as well.
I'm not quite sure yet, but it seems these are only supported with the most current browsers? If a customer visits with, say, IE8 or IE6, are they going to have an issue? (not that they ever should be, or that it would probably affect my purchasing choice; I was just curious because I'm seeing some old browsers and fielding some support issues now.)
Thanks, Alex