Most academic art and design classes are going to ask you to supply a paint palette to work with. If you go to an art supply store, these palettes can range anywhere from $5 - (gasp!) $15 each! While I wouldn't recommend cutting costs on brushes or paint, you probably can save money by using some 'home alternatives' to commercial grade art palettes. Here are some ideas of items you might have at home that would be perfectly suitable:
1. Take-Out Covers: I don't think whoever designed these realized the segmented pattern on the lid would be great for keeping paint separated, but there you go!
2. Trays in a Box of Chocolates: You know how you open a box of chocolate and each little truffle is housed in their own little compartment? They would be perfect for holding paint for smaller projects. Just remember to eat the chocolate first!
3. Egg Cartons: This is perhaps the most common alternative to paint palettes I've seen. The wells are usually nice and deep, and there's plenty of slots which makes it easy to mix enough of a color for certain projects.
4. Yogurt Cups: Yogurt cups are perfect for larger projects and are more shallow and made of a thicker plastic than the average plastic cup. If you have a lot of a mixed color you want to be able to save between projects, I would recommend taping a square of damp sponge or paper towel to some duct tape and taping over the opening of the yogurt cup to delay the paint from drying out and seal the moisture in.