Dow bathroom cleaner spray is about $2.50 for about 18 oz of bactericide at .01 percent concentration. Price per gallon: $17.22

The active antibacterial ingredient is dimethyl benzyl ammonium chloride. This is a quaternary ammonium chloride.

The same active ingredient is in HTH pool algaecide, quaternary ammonium chloride, 10 percent, a half gallon for about $5 at WalMart

That half-gallon will make 500 gallons of sterilizing solution for your home. 1 teaspoon per gallon of water is .013 percent. Price per gallon: $0.01. Yep, one cent per gallon. 1,700 times less expensive than the bottled bathroom cleaner. Sometimes I am not careful and use 1 tsp per quart because I use quart size spray bottles. At those prices, I can be less than precise.

BTW, I don't use quaternary algaecide in my pool because it foams too much - I get algaecide just for the house.

Don't like that chemical for sterilizing? Chlorine bleach at 50-100 ppm is an *excellent* anti-bacterial cleaner. A tablespoon of household bleach in a gallon of water will give that concentration. It is not strong enough to etch stainless steel. Bleach smell is very small and dissipates quickly. Don't fret if you use standard 5% bleach or ultra 6.75%. It is good for 2 days before the active chlorine dissapates, but what the heck, make up a fresh gallon each time so you don't use stale stuff.