Baking soda and vinegar are the two cleaners I keep on hand all the time. Besides being cheap, they're a lot safer to use than commercial cleaners and can be used for a lot of different things.
As an example, I clean the bathroom sink with baking soda, then rinse and spray vinegar/water mixture over it to leave a gorgeous shine. The vinegar removes water spots from the faucet, too. I use the same vinegar mix to wash the vanity mirror and clean the floor, using baking soda if there are scuff marks. I put baking soda in the bottom of the trash can to eliminate odors and I pour vinegar into the toilet bowl at night to deodorize, clean and disinfect - it also loosens buildup in the pipes. Baking soda cleans the tub, too, and vinegar keeps the shower walls free from soap scum and water deposits.
And that's just the bathroom.
I would hate to have to buy and store all of the commercial products necessary to do that.