One of the most limiting ideas I have ever had about art is that you need to have "professional" (i.e. expensive) art supplies. I have made many interesting things by raiding my children's left over art supplies.
One of my favorite low budget projects is Crayon Cookies. It’s easy and it has the added advantage or getting rid of all those pesky, left over, broken crayons.
Supplies-
Old broken crayons
Box cutter or scissors
Old cupcake tin
Cooking spray
First, I take all the crayon bits and remove the paper wrappers with a box cutter. Then, I arrange the crayons in cup cake pan that has been spayed with cooking spray. I heat the oven to a low setting. (Usually around 150 degrees.) When the crayons have melted a little I use a tooth pick to swirl them around.
They're also great for making crayon rubbings! Just find a textured surface (card board, bark, tupperware lids) and use the crayon cookie to rub the design onto a piece of paper.
The crayon rubbings can make really interesting backgrounds for collages. Paper collages are one of my favorite projects. I'm always on the lookout for interesting paper objects. Recently I found old playing cards with a holly hobbie type design for $1. The dollor store is also a great option.