Teaching unions said much of the support materials for the new National qualifications was online and had to be downloaded and photocopied from the website of the Scottish Qualifications Authority (SQA).
Alan McKenzie, acting general secretary of the Scottish Secondary Teachers' Association, said in some schools spending on textbooks had been curtailed to cope with the rising costs.
He said a typical subject departmental budget was around £3000 with roughly a quarter spent on photocopying in the past, compared to more than half now.
One example of the extra expense was a 13-page Administration and IT National 5 paper that schools will need to reproduce 25 times.
The Educational Institute of Scotland (EIS) has also reported that school departments are spending more on photocopying and printing - with English and maths particularly hit.
Larry Flanagan, general secretary of the EIS, said: "The SQA has effectively abandoned printed materials as a method of distribution, relying on its website.
"But schools often need hard copies to support teaching and learning, especially for pupil materials."
Mike Corbett, president of the NASUWT Scotland teaching union, said principal teachers around the country were reporting that the Nationals had led to significantly more photocopying, mainly because of the number of internal assessments. At a time when there is already pressure on school budgets, it is simply unfair to expect schools and local authorities to bear this additional cost," he said.
Ken Cunningham, general secretary of School Leaders Scotland, said new assessments inevitably led to extra work for schools.
However, he added that the burden was "more significant in these very tight financial times", even with the government's recent injection of £5 million to help teachers deliver the Nationals.
A spokesman for the SQA said: "We encourage practitioners to use the SQA website to access the most up-to-date documents for the new National qualifications. Given the extent of the support materials SQA produces, the website is the most environmentally friendly and cost-effective way of disseminating this information to schools and colleges."