Any+enzyme+assay+(without+a+spec)

Can we come up with an enzyme assay of any kind that can be done without a spec or radioactivity or expensive dyes/reagents?

Enzymes like alkaline phosphatase, lysozyme, and protease are often inexpensive. But the substrates that turn color are often expensive. Is there a cheap pair?

Could we do something with dietary supplement enzymes like papain or amylase? Perhaps show a decrease in carbohydrates with Benedict's reagent or IKI with color wheels or perhaps simply ethanol precipitation clods. Amylase is available in a variety of enzyme mixtures that typically include lipase, proteases, and galactosidase. Benedict's solution is a mixture of copper sulfate (used to kill algae in swimming pools), sodium carbonate (soda ash used in soils), and sodium citrate (Crystal Light). Potassium Iodide solution is available from PetSmart and tincture of 2% iodine is available at WalGreens for making IKI perhaps.

Perhaps protein by bradford or lowry with color wheels, or acetone precipitation clods. Making the unseen seen could help with any of the metabolic activities. A wide variety of proteases are available in different mixes and individually at health food stores.