How much is alliguna from Marco Polo airport to Ca Recconico please
14 EUR bought on-line, 15 EUR at the airport ticket window.
Flat rate to any of their stops on the main islands of Venice from the airport is as Sam says.
The webpage for their fares, stops, and route maps is at https://www.alilaguna.it/en/lines/lines-map
We also took the Allilaguna from the airport to our hotel. I had printed out a map of the airport so I would know where the boat dock was. It was much further out on the far left of the central area. You go on many mobile walkways until you reach the dock where the Alliguna boats are. You can buy your tickets there or at the ticket window in the main concourse area. I would suggest the main concourse so they can point you in the right direction. Yes, there are signs, but if you are having jet lag, it is helpful to have that extra help. Enjoy Venice!
I answered your question, but to answer a question unasked:- Barb's point, along with the fumes in the Alilaguna cabin, the almost zero visibility due to salt on the tiny windows, and the uncomfortable seating position down low, are why I now take the bus straight from the airport door to Piazzale Roma and a Vaporetto from there.
Faster, more scenic, cheaper. Much easier IMHO.