We just tweaked the terms slightly - we're going to keep track of our actual art costs (which tend to come in at $1000 but may be lower especially if you game has a bunch of art) and deduct that. So if the art cost say $750, we take the first $750 Apple deposits into our bank account and then 30% after that. Once the rev-share kicks in on every 99c spent on the game Apple takes 29c, we take 20c, and you get 50c.
My thinking is that a lot of games will need in app purchases for this to work out, so I'd imagine that's where most if not all monetary value would come from.
If a game is paid, we will switch it to free for a day or two during which the installs will be driven. This is a common promotional tactic (see freeappaday.com and others).
If the game is free then we'll just drive the installs when the developer wants us to. We won't require the game have IAPs at the time we start promoting the game (though of course we'd prefer it).
Does that mean you take 20% (28.5% post-apple) of the sale after the guaranteed installs and you take the first $1000 after the guaranteed installs?