Using CAN bus tranceivers with custom data link layer
Many small and cheap microcontroller have CAN built in.  Look at some of the PIC 18 with "8" in their part number.  You only need to add the physical CAN transceiver, like a MCP2551.

If you just want a differential signal, then you can use a number of differential line drivers/receivers.  There is nothing wrong with using CAN transceivers for this, RS-485 or others are options too.



Overall, I'd use CAN all the way.  You will need a line drivers/receivers one way or another.  CAN transceivers are as good as any, but then it's easier to use the rest of CAN.  The main difference with CAN is that the lower levels of the protocol have been well thought out and are available at low cost integrated directly in many microcontrollers.  RS-485 throws you a electrical spec, then you're on your own.

It's a lot more difficult to get all the details of a multi-drop bus right and robust than most people realize.  Use CAN.  It's all been worked out and done for you.  You send whole packets at the firmware level.  The hardware takes care of collision detection, retry, and CRC checksum generation and validation.  These are all things you want, and with CAN you get them practially for free.