Cheap biocide & corossion inhibitor drops?

Looking for cheap corossion liquids/sprays or drops and cheap biocide. Say under 10 dollars each.

Doesn't silver do this (at least the biocide part)? As long as you're not using EK blocks of course.

What I use in my loops.

http://www.frozencpu.com/products/11744/ex-liq-154/IandH_Dead-Water_Copper_Sulfate_Biocidal_PC_Coolant_Additive_-_15_mL.html

I'm using distilled water. I have copper, brass and stainless steel? Anyways. just find it scarey with this chart.

http://martinsliquidlab.files.wordpress.com/2012/01/corrosionplating.png?w=614

Distilled water alone wont work. Especially when mixing metals like that.