As far a big boards go 2 yrs ago our local hospital went on remodeling phase. They replaced 600 Solid core doors length was 10' I bought 3 of them for great building tables.

I think I paid 50.00 each flat as you could only dream of....only thing, heavy and don't even think about pushing a pin it, never happen. This set up will last for years and I will never use all of them. I know this don't help anyone, but maybe a good salvage yrd. might yeild a few.