Whenever I have to replace a server certificate I curse because I have to pay so much for so little. The whole industry is an conspiracy against the small businessman.
In the past I have purchased certificates from Verisign (very expensive), Commodo (not recognised on Android a few years ago) and most recently Digicert. However the cost of Digicert certificates is still high.
I read about StartSSL who have broken ranks and issues simple certificates for a single domain and one subdomain for free.
I created a certificate for
examplecustomer.elephantpm.com and elephantpm.com
and installed it into Apache on my Bitnami Ubuntu Server running on AWS and it ran fine.
The user interface and the StartSSL website is designed for techies by techies. You need to understand the concepts involved in creating and installing certificates. Where you see disparaging comments about StartSSL online I suspect that these have been made by occasional users. Indeed I suspect the majority of the cost of issuing a certificate is supporting clueless users.
StartSSL also sell a range of higher value certificates at a reasonable prices.
I strongly recommend StartSSL‘s services for technical users.