Atmega2560 based circuit and PCB design

I'm a software developer, with some experience in microcontrollers. I'd like to have a felxible but cheap GPRS based GPS tracker. I need a circuit, that can be programmed by USB like any Arduino board. The microcontroller would be an Atmega2560 (Like the Arduino Mega.) It needs to have the following modules integrated on one PCB: - SIM908 (GSM/GPRS + GPS) - GYRO for movement sensing, so the chepest available gyro can do(connected by i2c to Atmega2560) - MicroSD card slot connected to SPI - Lithium charger circuit for battery use (Atmega should sense if it is operating from battery or 12v) (Should be done by showing HIGH or LOW on one of the Atmega inputs) - smd on-off switch - 3 pcs of relay for 3 outputs of the Atmega - 3 pcs of inputs that can handle 12 volts - A circuit should be supplied by 12V The software would be developed by me, the only thing I can't do is the circuit and pcb design. All the diagrams are available on the internet, but in case of any questions, don't hesitate to contact me. The result should be a circuit diagram with a PCB design (eagle file) and a BOM list. The PCB should be as small as it can.