Wait! Stop! Don't get on that taxi. You can buy a bus pass for $7 per person and hop on and off the bus all you want all day long. It's a tourist destination, so they are very happy to stop the bus where you want to get off, and to pull over if you flag them down. You can do the Island awfully well on just a bus pass.

Mopeds were $80 per day. I declined. You could rent a car for less than that. I've had a car on the Vineyard on previous trips. That's fine. But you can get by with just the bus. And, on the bus, you get to visit with a number of interesting people and pet some nice dogs (everybody brings their dog to the Vineyard for Holiday weekends---who knew it was a holiday weekend? I didn't.)