I don't think you can judge a vacation cost as a whole as overly expensive. The flight costs what it costs. I live in a major hub on the east coast, and getting to Europe costs $1,000. Anything less than that is gravy.
To me, overly expensive comes into play with the lodging. $200 per night seems to be the sweet spot for a nice 4 star hotel in Europe. Just booked one in Amsterdam and Berlin; both beautiful hotels right in the middle of where you want to be for $200/night. Anything beyond that, imo, is overly expensive. We booked on in Florence a few years ago for $400/night and while it was lovely and my wife's favorite hotel ever, it was a little much.