Ed Hewitt Rule of Thumb
If the airfare is less than 10 cents or so per crow-flies mile roundtrip for long-haul trips, it is just about “normal", which for a lot of folks means slightly on the high side, particularly for non-essential travel ... that would be approximately $600 cross-country roundtrip, $700+ New York to London or $1,650 New York to Tokyo ... if the airfare is getting anywhere near five cents per crow-flies mile — $300 cross-country, $375 New York to London — that is the rock bottom ... the closer you get to five cents, the harder the fares will be to find, and the faster they will disappear... anything in between is probably going to work for most folks.