Are they worth it? If so, which are the best for the buck?

If not, why not?

I'm looking to get away from using AWeber (They've been doing some fishy things with my accounts lately.), and instead of using a similar carrier, I thought it'd be best for me to run it in-house.

I don't have a lot of money to work with, which is the biggest problem. I do have a mass emailer client, but I need a local SMTP server to use it (naturally). So, I'd like to find one . . . preferably one able to handle several hundred thousand emails at a time (I have roughly 1MIL double-opt-in addresses).

Any help?

It's appreciated.