Looking for guidance on designing a custom Arduino Mega board

I'm working on a project that is using an Arduino 2560 and I'd like to create a new custom board that has the following items all in a single design and was looking for some guidance. If you have experience with custom PCB designs and can take the 2560 eagle file and modify it for me please contact me with a price quote, otherwise any general suggestions would be helpful. Any idea what 20 of these boards would cost to build? Suggestions on a manufacturer?

Right now I'm using a Pololu VNH5019 motor driver shield and a Pololu Simple Motor Controller. I'll be driving 2 x 150W and 1 x 50W wormgear motors (low rpm, high torque). I'd like those motor drivers to be integrated into the board. 6 push buttons for menu control. I want to do hardware debouncing using a capacitor, resistor and schmitt trigger on each of those 6 digital inputs. 4 LED lights, put a resistor in place on the board so I can connect the LED light directly to the board.

I also have a design being built now that will connect to an ATX power supply and output to the motors and Arduino. I'd like that design to be integrated with Arduino also.

Look for “Crossroads” here. He does excellent design work and has made a couple of Mega-like boards with lots of functions.