The re-marking charges, which rise to pound;47 for a single A-level paper, have been likened to banks' controversial overdraft charges.
Isla Dowds, a psychology teacher from Helenswood school in Hastings, East Sussex, said: "I have candidates who most certainly deserve to have their scripts re-marked but cannot afford the risk of forking out. It is heartbreaking and frustrating to have to tell a student that, unless you pay, you can't have your results checked."
If pupils believe they have been badly marked, they can request a re-grade.
Although the cost is waived if their overall or module mark is changed, a loophole means that those taking re-sits or early modules may still pay.
On The TES online staffroom, teachers accused the boards of "profiteering"
and attempting to hide poor marking. "It is a total farce. The cost is simply to put students off," wrote one poster.
Mary O'Connell, a grammar school teacher in the South West, said her board refused to re-mark students' coursework for free, even though their grades had dropped inexplicably from C to E. "The examiner only sees a few pounds per paper, so where is this extra money going?" she asked.
Although some schools will pay for whole-batch re-marks, where departmental budgets will not stretch the cost can fall to pupils.
Average re-marking costs are pound;30-50, with pound;10 for a photocopy of the script. The AQA board said such charges "reflected the costs involved".
The Qualifications and Curriculum Authority will publish charges for all exam boards for the first time later this year.