I just watched a video where they explained that the public transport prices in Venice will increase Sept 1st. This would include the bus to/from the airport and the Vaporetto services. If you know you are traveling in Venice after that date, one money saving option is to buy your tickets (pass) now before the price increase. Your tickets would still be valid for the dates you choose upon arrival, but you will save a few euros.
https://www.veneziaunica.it/en/content/public-transport Is the website to purchase it from.
edited to add: Price of single use Vaporetto changing from 7.50 to 9.50 euros.
Bus from airport 10 euros one way.