I built SimplerSES for the same reason - a cheaper alternative to MailChimp using AWS SES. It's built as a hosted service so theres no server costs, and you only pay for the emails you send out.
Ideas: since you are competing on the price. add a graph showing emails/payment growing with you and mail-chimp/other strong competition side by side. next to it say "lowers is,of course, better." then you have to attack the main objection(IMHO), lower delivery rate. not sure how but you need to think about the "no one ever got fired for chosing IBM" affect and counter it. you can say something reassuring about SES. or have a quote from a user or two.
This looks like a great value. We were considering using Campaign.js, but actually getting it up and running on a server to fire out campaigns seemed like a pain (as does using sendy). Combining the affordability of SES with some symbolance of the UX of mailchimp seems like a killer value proposition.
This looks great. The biggest pain we had with MailChimp was dealing with unsubscribes from our website (i.e. anything other than an unsubscribe link in the email). How does your API handle unsubscribes? Do you simply upload a complete list of users each time and those not in the file are removed?
I built SimplerSES for the same reason - a cheaper alternative to MailChimp using AWS SES. It's built as a hosted service so theres no server costs, and you only pay for the emails you send out.