If you're in a school district that has a low budget for the fine arts this can come in handy. Here's a few tips on how to supplement your supplies for the year.
1. At the beginning of the school year, look up Reddits Gifts for Teachers. You can sign up for it, it's free, and a donor will donate supplies to you based on what you have requested.
You can find more information on Reddit's Gifts for Teachers here:
https://www.redditgifts.com/exchanges/reddit-gifts-teachers/
2. Donors Choose is a wonderful platform for teachers. It enables you to get materials for your classroom that you are lacking with the help of donations. Now this is not as easy as Reddits, you have to put some work into it. First they require you to sign up (it's free), and verify your employment at your school. Once that has been verified you can start a campaign. For your campaign it will lead you step by step through the questionnaire. Make sure you read the directions because it will send you back to do it again if you didn't follow them. Then you get to go "shopping". You can go to one of their affiliate pages and pick out what you want. Majority of art suppliers are on the list, so no worries there. Then when finished it will take you through some more questions. You will have to have the campaign approved by one of their staff members so this part will take a few days. After it has been approved you have to campaign for your classroom. Share to social media, send out an email to everyone, do what you have to do. You have to get those first small donations in there. Once you do, donors on the Donors Choose website will start adding to your funds. The best tip I can give about Donors Choose is to make sure you watch for donation matching opportunities and post them. Also when you get emails about special offerings like Chevron's Fuel Your School you MUST jump on it. Companies that do this with Donors Choose will usually fill your entire donation in one shot. Oh and one more tip. Keep your donation amounts low. If you ask for $1000 in supplies you're likely not to get it. If you ask for $400 or less it can get filled quickly. And if your donation doesn't get filled at all, it's ok! Try, try again.
After you get your supplies, make sure you follow the steps necessary for your campaign. They will want you to post pictures, write about your students experience with the materials, and in some cases they require you to have the students write thank you letters. Do not skip this ending step or they will not let you use the program again.
3. Hit up your local recycling center! If you're in need of supplies that you're not likely to find in a catalog, take a trip to your local recycling center and do a little shopping. Most items you get there will be free or very low cost. Items from these places will be more like your cardboard, plastic and metal containers, wire, paper goods (not the quality drawing/painting paper).
4. If you don't like the donation route you can always turn to fundraising. I don't know much about these because I don't use them, but there are definitely options. Here's a few I know about that you can look up. Make sure that you have approval with your school to do a fundraiser first as well.
Artsonia
Art to Remember
Square 1 Art
Original Works
Kids Art Fairs
Artome
Kids Kards
Silver Graphics
Kids Kreations
Here's a good chart showing you about them from The Art of Education:
http://www.theartofed.com/2012/06/08/the-ultimate-guide-to-art-fundraisers/
For information about Artome you can visit here:
http://www.artome.com/
For information about Kids Kards you can visit here:
https://www.kidskards.com/
For information about Silver Graphics you can visit here:
http://www.silvergraphics.com/
For information about Kids Kreations you can visit here:
https://kidskreations.us/
Good luck to you!