I use ServerTastic (https://www.servertastic.com/) for VeriSign certificates - cheaper than buying from VeriSign directly and it's the same "end product".

Other HN threads with suggestions:

"Ask HN: Where should I buy an SSL certificate for my site?" http://news.ycombinator.com/item?id=464916

"Ask YC: Why are SSL certificates so expensive?" http://news.ycombinator.com/item?id=530600