[onitica]

You might want to check out Microsoft Azure. I use it and it is powerful and has a good free trial. Only thing that is bad about it is fairly long deployment times (10 to 30 minutes). As a disclaimer I currently use it with C#, but it recently added support for python. Other than that, Heroku is a good choice. Google App Engine may be another possibility, though I haven't used it nor do I know a lot about it.

For e-mail I recommend Sendgrid, you can get 200 e-mails a day free. Also easy to integrate in.

For payments I've used Braintree and I like it. I didn't set up the account but I was given a sandbox account to try it out and it should be possible to get one. Easy to use, especially if all you are doing are transactions (even though subscriptions aren't bad on Braintree either).