I put together a google docs spreadsheet that is similar but built for subscription startups:

http://spreadsheets.google.com/ccc?key=0AumfOxrn5FGtdEN5U21L...

You enter your subscription tiers (3 by default) and what percentage of users will choose each tier.

It spits out projected revenue, Braintree fees, paypal fees, and then adds Spreedly/Chargify into the mix so you can switch seamlessly.