The reason I mentioned the Air Gradient DIY Pre-Soldered kit is that most if not all of the tinkering is done for you. The main PCB is all pre-soldered and all of the standard sensors are included have the pins headers soldered on. You can literally have that sensor up and running in less than 5 min. All you have to do when it arrives is push the pin headers for the sensors into the board, Screw it all together and power it up with USB-C. When it boots up it will give you a Hotspot to connect to complete the setup and attach to your wifi. After that it just runs and reports to Air Gradients servers. If you then want that kit to attach to HE you have a few additional i outlined [here](Air Gradient integration with Maker API. Those steps are pretty straight forward but do require a little bit of setup.
The nice thing about the AirGradient DIY sensors is that if you don't mind a little bit of soldering you can get just the sensors you want and attach them. The two most expensive sensors in the device are the PM2.5 sensor and the S8 CO2 sensor. Even on aliexpress those two can be fairly pricy. The Air Gradient kits also come in a variety of setup based on if you mind doing a bit of soldering. You can get the basic version for $1+shipping if you want and then just get the S8 sensor and a microcontroller.
If your hope is to stay under 30 that will likely be quite difficult.
