I need to build 100 coach tracking devices. I am a web/mobile programmer, not an engineer, so I'm going to be looking at outsourcing for this. To outsource this work however I should know the components I'm going to need in the device (I am able to program the device). As I'm outsourcing I need to consider the price/quality of the components, ideally I need to pay as little as possible (to state the obvious).
I need the device to send its current latitude and longitude coordinates to our servers along with the registration of the vehicle the device is inside.
1) Cheapest way to transmit the vehicles position/registration?
From my current knowledge, I think the three channels to do this are a 3G/4G network, SMS or radio. If I'm transmitting the vehicles position and registration every 30 seconds, which would be the best compromise between accuracy and price?
2) The microcontroller
At the moment I only know of the Raspberry Pi and the Arduino. Are there any other perhaps cheaper computers more commonly known for wholesale? I simply need a cheap component that sends the vehicle's registration and its location.
I can't comment on power just yet as I don't know what power is available in the coaches.
I would really appreciate any advice/ideas. Thanks