Sand: There's no local sand source that I have found and while everything else can be procured through local foraging, sand has to be shipped in. Everything from passive filtration systems, smithy work, making bricks and cement, cob home building, not to mention the natural abrasive and reusable properties of sand and I'm seriously looking into having a mound delivered into the spare part of the barn. I'm trying to build new outbuildings out of earthbags (I ditched the cob idea, due to portability concerns) and sand will come in handy for parts of it.
Sodium borate (Borax): I always keep some around as a detergent additive, but it is also a fire retardant, anti-fungal, curing agent, treats thrush in horses' hooves, insecticide, can be used as a fertilizer in boron poor soils, and that's just the beginning. So I need to find a large scale supplier since buying it by the box would not be cost effective.
Filters: Of every sort. Air filters, water filters... you name it, we just got over the 6mos mark in supplies so if we have to go for longer on well water, well let's just say we'll be crunching what we drink. They're cheap enough to acquire so this is simply a lack of organization showing. Also I lack enough flour sack cloth, cheesecloth, cotton batting, polyfill and other such fabrics. Since I can't envision tolerating life without cheese (well I can but I opine that if I'm preparing I'm shooting for comfort not just getting by, so even if I fall short I'll be better off) I need at least one of those for cookery. I plan to shore up old discarded sleeping bags, tatty comforters and the like vacuum sealed just in case. Plus, it's cheaper. Also if I need to fashion a water filter or even an air filter, I can figure it out.
Yeast: I need to acquire the patience to keep a running stock of live yeasty beasties. All my old starters died. While I have some around, my basement is proving very damp, nay wet, so a lot of my dry goods went south. Part of my yeast stash was in the mix so I'll need to restock.
I'm sure there's more but when one is in the middle of a circadian reboot, composing coherent thought is hard.