This is a one page list of supplies I have found helpful over the years for various STEM activities. Keep a copy on your phone or print it and keep it in your bag for any time you are out shopping. Previously only available on my blog, I have added the list here on TpT for convenience. You can read the original post here
Don't forget to use your teacher discounts wherever possible! If you aren't sure if there is a discount program where you like to shop, just ask. I have found more and more stores participating in discounts for teachers. Homeschooling parents, you can access many of these discounts as well! Here is a list of some stores
that offer discounts. Please double check with your local store just to make sure they are a participant.