The best thing to use for a 'home made' cutting edge is a piece of T1 plate. It's not cheap but it will last longer than a piece of plain old mild steel. Your biggest problem will be that you'll either have to torch cut a bevel on the leading edge, or have someone machine a bevel on it, otherwise all you'll have is a square edged 'cutting' edge that won't cut anything.
That said, do some checking around, you should be able to find factory replacement cutting edges without alot of problems. You might have to get one a bit too long, etc and cut to fit, but something close ought to br available.