It sounds like a really good project.
Z-Stack, which is the ZigBee library for the CC2530, currently can only be used if the firmware is compiled with IAR. IAR a well known compiler for embedded development, however it's expensive and so adds to the cost of development. I.e. developers have to pass the cost onto their clients, and clients can't make small changes themselves unless they also buy a license.
My preferred way to do it would be to use an ATmega256RFR2 in place of the CC2530. This is a similar MCU/RF chip, for which there is a ZigBee stack that can be used with avr-gcc, an open source compiler.
Is the design of the USB dongle also required as part of this job?
For the USB dongles I would suggest basing it on the CC2531. Afonso et. al used a CC2530 plus an FTDI chip. The CC2531 has USB built-in, so eliminating the extra chip. There is a stock firmware from TI called CC2531-ZNP which gives access to the ZigBee network using a serial protocol through the USB port.
Such dongles can already be purchased ready made, so you have the option to either buy them in or make them.
In addition to the schematics, firmware source code and BOM, I will also send PCB gerbers and Eagle files. I'll get the PCBs made, build a prototype and send it on to you.
About me:
I have over 20 years experience as a developer. I have a degree in mathematics and I'm currently studying for a degree in physics (5/6 complete).