Use
Sendy +
SES. You will never get it cheaper, with better delivery and Ben is great. He can help you set it all up for cheap.
If you don't want that, I can hook you up and you can use my installation - currently I can manage up to around 50K a day:
I am sure I can beat anyone of those that try to pimp overpriced poor solutions. But really, you can get your own for peanuts via Ben (the guy that wrote Sendy).