This report might give you some more ideas for your wish list. (PDF alert)
Greetings, fellow teacher at an urban charter school! Although mine’s about 2000 miles from Phoenix. 
In lieu of financial help, I hope my advice will prove worthy. My husband and I instituted a new “library” at our school, which now comprises 8 big bookshelves of books! We contacted every bookstore in the area for help as well as having parents drop off books they no longer wanted. If you have a Half-Price Books in the area, I recommend contacting them first as they contributed a LOT of great literature to us at no cost.
Local bookstores may also be willing to donate, just gotta ask.
Using my one bump to get more views!
Polly Glot, thanks for that advice. I’m going to try that this weekend.
Mailed mine yesterday, I imagine it’ll be there in about a week.
You might want to check this out:
Paperbackswap.com’s school book program.
If paperbackswap members donate credits, the management there can use it to purchase new books for the schools. It’s worked well for 26 schools so far.
I have tried to get it going at a school here in Chicago, but the site’s founder told me they probably won’t actively sponsor a school again until the August/September timeframe. Still, if you apply at the end of the summer, it might mean 500 books.
Least I could do! Now if we could only figure out a way to get kids to* read* 'em, we’ll have done pretty good 
I’m just clearing out bookcases and was going to take some boxes of books to be donated. PM me the school address and I’ll send a suitable selection to you.
My kids have moved out and promise me that they’ve got everything they want with them already.
I’ll try to round up some books for you.
non-fiction books OK?
Yes, non-fiction is great!