Roughly half the amount that the nation's public school teachers are spending on educational products is being covered with their own money, a new nationwide survey shows.

All told, teachers spent about $3.2 billion on various types of supplies and materials during the 2012-13 academic year, according to the survey, released recently by the National School Supply and Equipment Association. Half that total amount, $1.6 billion, came out of educators' own pockets.

The per-teacher breakdown is as follows: The average educator forked out about $198 of their own money on instructional materials, $149 on school supplies, and $139 on other classroom materials, for a total of $485 last academic year, according to the survey.

In total, nearly all teachers—99.5 percent—reported digging into their own pockets to cover the costs on classroom supplies or materials, according to the association. The portion of teachers doing so appears to have risen over time.

The report, "The 2010 NSSEA Retail Market Awareness Study," was based on a survey of 308 K-12 teachers, conducted by Perry Research Professionals.