Travellers are progressively buying inexpensive flights offered by budget airlines at travelling agents and on the internet.
But Warwickshire Trading Standards is warning that the "extras" on some low-priced flights can finish upward making them more costly than those offered by much conventional airlines.
And they seek airline companies to publicize more understandably to customers.
The admonition comes after covert officers from the service visited travelling agents in Rugby, Leamington, Nuneaton and Stratford, as easily as looking at deals accessible on the internet.
There can be extra booking charges for paying by credit card with some airlines charging a flat fee and some charging a percentage of the total cost.
Luggage allowances have been cut on many airlines, with charges for exceeding set limits. Travellers may also be charged extra to book a preferred seat.
Trading standards officers said they found it possible to save 43 per cent by booking with bigger, non-budget airlines.
Mark Ryder, head of Warwickshire trading standards, said: "We call upon the budget airlines to make their advertised headline prices clearer, so the average traveller can see just how much they will have to pay and can compare prices.
"Our advice is don't be drawn in by enticing offers. Shop around before you book.