I think you'll save money using the proper, high strength stuff. Let's say that the 3% stuff is about $3 for a 250ml bottle. Just 3% of that 250ml is H2O2 (7.5ml pure H202, the rest is water), so at that $3/250ml rate, you're paying 40c per ml of pure H2O2. I buy 50% grade H2O2 for $5/litre. 500ml per litre is pure H2O2, so each ml of pure H2O2 costs me $0.01 (yes, 1 cent).
Apply the same logic you do in troubleshooting. You wouldn't arbitrarily ground pin 268 of your computer's CPU IC just to find out what happens without first consulting the pinout diagram, would you? No, of course not. Research and know instead of jumping in blind.