$ git push master heroku
is a lot cheaper then:
Setup a machine. Then setup mysql, nginx, REE 1.8.6, or did you go with MRI 1.9.1? You're not gonna launch on Rails3 right? Because then you can't do 1.9.1, you have to go to 1.9.2. And you know how to setup nginx to pipe requests through to a Rails app. Are you going with Passenger or Unicorn? Oh make sure to bring up another machine to act as a MySQL slave. You know how to do that right? And you're dumping your DB to disk and backing up to S3 regularly right. Just write a simple script/cron job to handle that. And when you setup your machines you made sure to setup 2 so that if one goes down, the other will still be around, and you setup a load balancer that will realize when one of those machines goes down right?
etc.... :)