Not attacking the guy, but I know for a fact "email blasts" cost nothing if you have an Internet connection. I could send one out to a billion addresses if I had them, and it wouldn't cost me a dime. They may look nice and elaborate, but emails are nothing more than formatted text, without attachments they use virtually no bandwidth.
If you do it yourself and you use your own list you can do it for next to nothing. If you use a service like Constant Contact, which is an excellent email service that I've recommended to different people to include a congressional candidate who now uses it, it isn't exactly cheap. It offers email campaign management, easy formatting and creation of email with graphics and other professional-looking elements, it tracks what emails get delivered, what gets bounced, and it even tracks the click-thrus on the links within the email. I know that if I was sending out campaign or fundraising emails to a large list, I wouldn't do it any other way.
There's a good possibility that Simcox purchased email "blast" services from the same company that he's using for direct mail and web-based donation services. And I'll bet they charge a pretty penny for rental of their email lists as they do their direct mail lists.