I think defining the requirements a bit closer would be useful.
Is this for temporary use in a building or permanent installation?
What is to be measured? Temperature, humidity, moisture, CO2, wind speed, insolation, electrical appliance consumption, water consumption, door openings etc.
What size of building? I doubt the same solution is likely to be appropriate for both a single dwelling and an airport terminal.
To what extent is low cost permitted to be achieved by DIY construction, installation and operation?
Are any standards required to be followed for the measurements?