Two-thirds of families felt "ripped off" during their last overseas holiday, a survey has found.
Some 67% of people surveyed by Post Office Travel Money perceived they had received poor value on an aspect of their trip.
Food and drink prices during flights were found to be the biggest gripe in the survey, followed by excursion costs, transport charges, compulsory service charges added to meal bills, charges abroad for cash withdrawals and meal and drink prices in restaurants and bars.
Poor exchange rates were another annoyance, as was the cost of buying extras such as buckets and spades when families hit the beach.
Andrew Brown, the Post Office's head of travel money, said: "The key to saving money is to think back to those budget-breaking experiences on past holidays and take steps to avoid getting caught out again.
"Do your homework between now and the school holidays and you could avoid overspending by hundreds of pounds when you get to your destination."
More than 2,000 people from across the UK took part in the research.