A teacher's paycheck is never her own

As I begin to pack up my classroom for the eventual departure from my current school, I am realizing just how much of my own money I've spent on "school supplies." The sad thing is, I am not alone. Teachers don't make a lot of money; that's common knowledge. The crime is that, of the little they do bring home, they spend so much on making the classroom welcoming.
For instance: I love to read novels aloud with my class. The school has some novel sets. But I have spent upwards of $1,000 on novel sets alone. I hand them out to my students and HOPE they return them when we're finished studying the novel.
Another example: My classroom library does not contain any novel sets. Those are separate. I have already packed up four enormous (nearly too heavy to carry) boxes of books. These I may have one to four copies. Again, the students check them out of my classroom library, and I HOPE they return them when they're finished.
More: Science experiments. I don't teach science anymore, but when I did, there were always supplies I needed for which the school didn't pay: aluminum foil, paper towels, plastic cups, light bulbs, squid. Yes, my fifth graders dissected squid last year. We had lots of fun. I went to a grocery store in Chinatown and bought the squid, refrigerated them overnight, then carried them to school in a cooler. It was fun, but expensive.
Every job has these little irksome truths. Teachers have settled for low pay for generations, because most of us are so dedicated to our students and want them to have the best educational experience we can provide. As a society, though, we undervalue education. When we shortchange those who provide our future with the discovery-based lessons they need, we shortchange the whole country's future.
Aside: This practice is not limited to "underprivileged" schools. Teachers in some of the richest districts in the nation have thousands of their own dollars pouring into their classrooms.
Hidden benefit: As I pack up my classroom, I hope my principal is walking by and noticing how bare it is becoming. Yes, you axed me. I'm not leaving a poster, a paperback or a marker that doesn't belong to the school. I'm taking it all...along with my pride.