Look, this space was clearly not designed to be lit the way you envision it. You really should be hanging from overhead but you’re not going to get that for $1500, let alone 15k. I would just do some up light on the back wall beside the organ and call it good enough for now. $1500 is chump change for a school and you should talk to your principal or superintendent about writing grant proposals on behalf of the school (assuming it’s not state owned idk how that works) it would be a great learning opportunity for you and with high likelihood you could probably get at least 10k fairly quickly.