The cost of those sensors are cheap, below $2 for each sensor. Items a bit more expensive are ESP8266 and 18650 Lithium battery.
Here are the full list of materials as a reference:
- 2x Light Dependent Resistors with 2x1kΩ (pull down)
- 2x TSL2561 Luminosity Sensors
- 1x BH1750 Luminosity Sensor
- 1x TEMT6000 Light Sensor
- 2x DS18B20 Temperature Sensors
- 1x DHT21 Humidity and Temperature Sensors
- 1x Si7021 Humidity and Temperature Sensors
- 2x LEDs (Read & Blue) with 2x ~220Ω
- 1x I2C ADS1115 16-bit Analog-to-Digital Converter (ADC), ~$1.6
- 1x TP5400 5V Boost-up Lithium Charger, $1.32+ a piece
- 1x ESP8266 WeMos brand, ~$3
- 1x 18650 Lithium Battery, roughly $5 a piece
- 1x Push-lock Switch
- PCB Dev Board, wires, soldering wire, multimeter
- Plastic box (I used a box used for convenient foods)
- Ready to spend your next week for the whole process
The cost of parts is about $25. After soldering this is how my weather station look like:
I attempted incorporating two TMP36 Temperature Sensors but the reading was off a few degrees. Maintaining a precise 3.3V is the key.
I did not know I2C multiplexer - I2C expander when starting the circuit. That limits the number of Si7021 or HTU21 Humidity and Temperature sensors. They are using x40 (60) I2C address and no reconfiguration available.