In this project I'm using some API's and spreadsheet reader Sheety, to send you an email whenever a flight's price is below the price you're willing to pay. You can put your own information in the code and try yourself.
Firts you'll have to create an account on this websites and get your own API's and ENDPOINTS:
Tequila: https://tequila.kiwi.com/portal/login Sheety: https://sheety.co/
Now all you have to do is replace wtih your API's and enjoy.
Obs: Have a look at your spreadsheet's headers.