Is this a different product from AWS SNS ($1.00 per million) or Twilio push (10000 free per month, then 0.00025 each)?
Amazon SNS is not a competitor of Notify17 in first place, because SNS is a general purpose publish-subscribe system, while Notify17 is a solution that accepts HTTP payloads, and processes them to generate notifications, which you can see in a web browser or on the iOS app (in future also Android one). They're conceptually a lot different.
Because of this core difference, I cannot say there's any plan to compete with SNS.