If you're not overly-concerned with the armor being able to stop live steel, look into aluminum flashing available at most hardware stores and home centers. It comes in rolls of varying widths that you can cut with cheap metal shears and punch holes in it with a nail. Just make sure you sand the edges.
For armor-grade metal, my main steel supplier when I used to make armor was Fazzio Steel in Glassboro, NJ. They sell (sold) scrap aluminum and steel sheet metal for $1.50 per pound (They are an industrial sheet metal company, so "scrap" metal for them can be the size of a large shield.). However you will still need tools and a shop to cut the metal into workable plates.
__________________________________________________________
OOG: Drew C.
"I don't always NPC. But when I do, it's for years at a time."