Acid brushes are about 12 cents each. Use them to apply grease. Use them to apply glue for tubular tires.

Brass-bristle brushes are great for cleaning aluminum and steel without scratching. They help with removing rust, especially from tight spaces. I get these in the plumber's aisle at Home Despot.

I don't need no stinkin' hand cleaner. I use soap or dish detergent, and while scrubbing, I toss in a handful of baking soda. It works great, and it's not abrasive. It's extremely cheap. I keep a jar of it by the kitchen sink, and I don't put the lid on.