Dollar tree has individual colors of bingo dotters for a $1. They don’t say non-toxic and they don’t say washable but they’ve been fun for my older kids (11, 8, 7) to play with. I think there’s only 5 or 6 colors. Just another cheaper option for the do a dot markers if you’re comfortable with your kids playing with them.
As far as supplies, we replenish all of the basics and then I look at each curriculum and determine what I’ll need. For example, the writing curriculum my daughter uses required a binder, divider tabs, lined paper, and a comprehensive thesaurus. The art curriculum I use with my younger two has a supply list already in it so I just bought what we didn’t already own.
I also buy any supplies that I will need to replenish throughout the year…toner, colored copy paper and card stock, page protectors, etc. I used to buy laminating film a lot when my kids were younger and I laminated more, but I don’t need it as often now.
Another thing you can do is figure out how you will organize all of this and then buy the supplies to make it happen. For example, when I bought the bingo dotters, I went ahead and purchased a plastic container with a lid to put them in along with the art paper they’d be using the dotters with.