Plaster, rarer than hens teeth
Having just paid £132 for six bags of plaster ( yes really) it probably is worth more than gold atm, the gypsum factory closed as with everything else and there was no plaster to be found in any of the diy stores, selco in York had some when it reopened, but someone drove from Essex ( we were still in lockdown and no long distance travel) and took the lot, it’s going for megabucks, four bags recently went for £175 crazy, but were desperate for plaster as our kitchen is being fitted in a few weeks, it’s madness...
Btw, bags of plaster, 25kg, are normally £7 50 or so...