A more affordable method would be to attatch a wire bristle as an abrasive to your drill. A good industrial grade primer with corrosion inhibitors to prime with followed by your topcoat. PPG, Sherwin Williams, Bejamin Moore as well as others make decent primers that prevent rusting. I like to also apply a topcoat that contains an anticorrosive pigment like the primer if possible. This makes a better package. I am a coatings chemist and know quite a bit about paint but for certain, when doing as many things on your own can save you some money. I must also agree that coating the newly exposed metal ASAP with primer is very important to prevent future rusting. There are some corrosion inhibitors that can be painted over rusted steel (we make them) but applying over clean metal is the way to truly avoid problems. As far as polymers go, I've always been more impressed with alkyds (oil based solvent coatings) but water based technology is really super these days. The problem with industrial solvent paint is they may contain hazardous and volatile organic solvents, mineral spirits would be good if you can find it. Water based paints are more user friendly but getting the appearance, flow, and even corrosion protection may be more difficult unless you get in with a big paint manufacturer. The bad news is they (big companies) may not wish to fool with someone buying 5-10 gallons of paint but there are willing companies out there. Good luck.