@creationtwentytwo: If you're developing an iPhone game the minimum upfront fee for Unity is $400 for the basic iOS license: http://i55.tinypic.com/2vkcf3s.jpg
I think it's 25% of all sales after $5000. But the most important factor is that UDK is free up front, whereas Unity Pro is $1500, + $400 for iOS or $1500 for iOS Pro. So a minimum of $1900 up front before you've even published your game. Add in this new 20% for Union, and then look at how much it would cost. If you sell…