Casa Santa Maria Formosa

Their web site has explicit instuctions with pricing.

http://www.casaformosa.com/en/location.htm

They don't price the private water taxi but the current rate is around 100 euros.

Here is the advice from the hotel.

http://www.casaformosa.com/en/location.htm

If a (very expensive) water taxi is out of the question, the Alilaguna ferry from the airport is usually the simplest way for that end of the city ie as opposed to the bus plus vaporetto option. Either way you are going to have to walk to your hotel from the vaporetto (water bus) stop.