Budget for a flight from New England to Greece 2019?

Fly Round-Trip to Athens and buy your Santorini-Athens ticket separately from Aegean Airlines or Ryan Air. That's the least expensive way to do it. Spend all your time on the mainland for the end of your time in Greece so you aren't scrambling back to Athens a the last minute for your flight home.

That sounds like a lot, but it really depends what city you're flying from (some cities are just too small of a market to be inexpensive). If you can fly Turkish Air out of NY, you can shave some of that cost. There's no way to price flights for August 2019 this early, and if you were to look right now for 2018 flights as an indicator, you may be seeing higher prices because you're looking out less than 3 months away (which is not a lot for a peak season flight). Start looking say in March or so next year and track prices over a few months...that will give you a better sense of a good fare.

On the other hand, it can't hurt if you budget for $1,400 and shoot for saving that much. If you're over your mark, you can put that into savings or elsewhere.

On average I budget for airfare to Europe from New England to be in the range of $1200 round trip. I generally fly out of CT and many flights are about that much.

I use a third party site to book my airfare. From my experience I've never found going to the airline to be any cheaper. I use cheapoair. I put in my destination and get alerts when airfare drops. I'm going from JFK to Thessaloniki then Athens back to JFK this September. Round trip tickets for $500. I've been very lucky for my last two flights getting flights around $500. Doesn't happen all the time though.

From Anchorage to Oslo we paid $1,200pp in July on Iceland Air. This same flight (6 omths later) is now returning from Glasgow $1,800. I think the sooner you book, the better!

August will be more expensive to fly from New England to Athens. I fly out of Boston and go in October. This year I got a ticket for round trip to/from Athens for $663 for American Airlines with a short layer over each way and could pick my seats at no extra cost. However, I booked many months in advance.

Your best bet is to book a separate fight from the US and then book a flight from Athens to Santorini, probably Aegean Airlines at a better cost. It's possible you can get a flight to Santorini after landing in Athens if you have at least two hours between flights.

However, going back to the US you want to get back to Athens at least one day before flying home in case of any type of delay.