My other hobby is restoring 1940 to 1950's Vintage Camper Trailer's. What your talking about is exactly what is happening to that hobby today also. $100/sheet for plywood. $400/gallon for quality automotive paint. $600 for quality dense seat/bed foam. $2000/for new aluminum body skin. $1000 each for 100 amp hour Lithium batteries. Without any sub'd outside labor counted, you can easily speed $20K just in material costs to rebuild a small sized vintage camper trailer at todays costs.
John