Try contacting NAEA or your local state chapter regarding the dolllar amount spent per student.
At the PAEA(pennsylvania) conference, there was some mention about there being a survey done a few years ago on this and other pertinent data important to Art educators.
I'm going to try to find out myself, to arm myself for the next budget meeting !! This year we were cut 47% across the board....ARGHHHHHHHH !
Good luck, hope this helps, Chris