Step 1: Materials
Pipets (Can be purchased online from all kinds of vendors. Example: http://www.flinnsci.com/store/Scripts/prodView.asp?idproduct=14269 About $25 for 400)
You could substitute syringes, turkey basters, or some other device that would allow you to add the liquid to the bottom of a tube but pipets are so useful you might as well buy some if you don't have them.
Useful (but could substitute):
250mL beakers (4-6 of these)
Salt (about 36g = 6 Tablespoons)
Cups or bowls instead of beakers
Natural dyes instead of food coloring (Think beets for pink etc.)
Sugar instead of salt (This is a little messier and if not well cleaned up more likely to be a problem but works just as well.)
Spoons instead of stirring rods.
Any kind of spoon that you use could be substituted for measuring spoons. You just need to know that you're adding a relatively standard amount more for each additional color.
Electronic Scale or Triple Beam Balance for extension
Test tube rack
Test tube drying rack
Test tube brush (for cleaning)
These optional ones are more about teaching them about these pieces of laboratory equipment.