Or, if you can master the Art of the Squeegee, that's even cheaper. Using a sponge or rag, rub washing soda onto the tiles, and rinse well. Fiberglass Cleaner 1 cup borax, vinegar to moisten. Place borax in a bowl or container, add vinegar to moisten. Using a rag or sponge, rub borax mixture into the fiberglass, until clean.
Salt is an amazing thing.
And it's not just for seasoning anymore, it makes one stupendous cleanser. Salt can also be used to deodorize drains and garbage disposals, just by pouring half a cup into the unit and following with boiling water. This is one very fast way to obtain nice and shiny copper, for pennies. Combine the three ingredients and keep them in a tightly closed container. Use as you would any commercial scouring powder.