The first thing that comes to mind is checking at the local farm store for some poultry wire fencing. You could go as cheap as chicken wire and wire tie it to a cut-to-fit cattle panel. You might have $50 dollars in it. I know the cattle panels can be bought galvanized.

Light duty (cheaper) expanded metal may still be kinda flimsy and need some sort of reinforcements, but would certainly look more professional.

Fish on!,
Noel