Plenty of folks sell replacement sheetmetal.
Lemme see what I can dig up for URLs..
I have a pricelist from.. hmm.. dunno when.. from SSS.
Half-floors for $35 (L or R)
Front floor w/ lip - $65 (L or R)
Also front body mounts - $55 (L or R)
Floor support "stringers" - $38 (L or R)
I'd call them and confirm the prices, of course!