Ask HN: Best certificate authority for personal web/email server?

I've decided I want to run my own email server for my personal consulting business. I'll be hosting on EC2 and have applied to remove the email limits from AWS.

The CA space is dizzying and seems like all options are drastically overpriced. I'm leaning toward the free option from startcom. Would this be fine or should I bite the bullet and go for one of the majors like verisign, comodo, thawte?