Flight
The cheapest flights we have found (from the U.S.) is to fly into London and then buy another flight from there to Greece. You can also look on Google flights where it will show a map with the different pricing. There is also the option of flying into Athens International Airport (ATH) and taking the high speed ferry to the Island, which is about a six hour ride. It is fun but also takes longer than a quick flight (plus the ferry is oftentimes late).
Hotel
We have a Wedding hotel booking page with specially negotiated group rates. These rates can fluctuate and sell out at any time, so make sure you book sooner than later! It only takes about 35 minutes to drive from one side of the island to the other, as it is small and everything is relatively close. The Wedding ceremony will be on the Caldera (more pricey part of the island) just FYI when looking where to stay.
Rental Car
If you are interested in renting a car, which may be the best way to get around the island, rather than busing, you can rent a small car for under $200 for a whole week.