Most food mills these days are made from stainless steel, some are plastic with stainless steel plates, so rusting isn't going to be a problem.
My only advice is to buy a good heavy sturdy SS one (probably going to run you $50-$90) not one of the cheap light $20 models. My XW had a good one that I got used to using and after our divorce I bought one of those cheap ones ... I threw it in the dumpster after using it 3-4 times.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain