Cost of a sensor including battery and plastic case 16USD. Search this on aliexpress " LILYGO®TTGO T-Higrow ESP32 WiFi And Bluetooth Battery And DHT11 Soil Temperature And Humidity Photometric Electrolyte Sensor"
Note this is slightly different format from the BeardedTinker video and instructions, guessing there have been some changes to the TTGO-HiGrow-mqtt-master-mac-id-autodisc.ino file.
i am making similar with LoRaWAN too, all works up to The Things Network but so far i could not fetch the data from Home Assistant. I will post a question separately as its LoRaWAN topic, not WIFI