I would assume the development alone of a working prototype that is able to collect some interesting data and transmit them from isolated locations (appeared to be the main idea) will cost in the range of 20-50k $.
I could do it for much less, based on commodity hardware like the Raspberry pi or other arm-based minicomputers and commodity sensors.
5-10k for development (1-2 months of work), around 150$ hardware costs for the device per unit.
What state is the middleware/condensator in? Could we just use MQTT?
Please keep the IoT idea, this is what makes this project special.