Fares on round-trip tickets can depend on where you start which further adds to the confusion over air fares.
An example: The average price paid for a Los Angeles-Honolulu round-trip ticket was $614, which is 7.5 percent higher than the $571 average ticket price if purchased in Honolulu. according to a study commissioned by The Wall Street Journal.
Between New York and London, travelers averaged paying $2,507 if they started in New York and $1672 (50 percent less) if departing from London. Travelers leaving the US for Tel Aviv paid 28 percent more ($354) than those leaving Israel ($1618 in New York; $1264 in Tel Aviv).
There is no cost difference to the airlines for round trips no matter which direction is flown first. On the most popular domestic markets, the average price variation by direction was just $18 or 3.5 percent of the ticket price.