My volume is low enough that I fit in their free tier - Amazon was only a few bucks a month but if I can get the same quality of service for free, I'll take it. Mandrill also seemed to provide a bit more utility than SES, which came across very barebones. Mandrill has reporting and some other neat features built into the service.
44K less 12K free = 32K @ $0.20/thousand = $6.40.
Maths not important, just wondering if you've got a better deal than 0.20 per K by coupon or something.