With recent developments brining Internet security into the spotlight (such as heartbeat), SSL certificates are easily one of the cornerstones of any Internet-enabled application.
Unfortunately, a simple Google search does not easily reveal the best options for obtaining SSL certificates. Thus, I have compiled a small list of popular SSL certificate providers.
StartSSL seems to be the way to go to get a free SSL certificate. Their desktop browser support seems reasonable but there might be problems with some mobile browsers and applications.
Low Price < US$10
Low price SSL certificates (for domain validation) can be obtained from resellers. GOGETSSL and namecheap seem to be good options. In my understanding, these issue essentially identical certificates to those obtained directly through RapidSSL or Comodo.
Medium Price < US$100
Further popular providers for SSL certificates are GoDaddy, RapidSSL and Comodo. All of these offer solid certificates trusted by most browsers and platforms (though, at present, GoDaddy certificates are not supported in the latest JDKs).
This list is specifically about the most basic form of SSL certificates, which only validate your domain and not your business name. However, I think for most applications these are more than enough. While for domain-only verification I would recommend the low-price options listed above, for business name verification I would recommend going directly to a more established provider.