good advice for finding sustainable, local textile production
There largely isn't any of this. There's really very, very little in the way of locally-sourced textiles, and what there is is going to be art rather than functional. I don't know where you live, but in the US, there are only a handful of mills that remain, and you'd need to be placing a mill order (e.g., hundreds or thousands of yards of fabric) in order to do business with them. OTOH, there are often local tailors that will be able to order high-quality textiles to make bespoke garments for you. The downside is that this is REALLY expensive. For instance, I'm a bit slow at patternmaking, and not the best at fitting, and if I charged only $25/hr, you'd be looking at around $100 for the initial sloper, and probably another $150 to tune the fit. From there, patterning for a specific garment can take a day or more, depending on what you want, and that's not including cost of materials and sewing time. For a bespoke suit, you're starting at about $5000 from an experienced tailor.
That aside, there are certainly a large number of things that are buy once, cry once. Take kitchen knives; if you buy a Yoshimi Kato nakiri, a good set of Shapton glass stones (...which, TBF, will probably cost well over $1000), and take care of it, it will easily last your entire life. If you buy furniture from highly skilled carpenters, you'll likely be buying something that will last over a century as long as it's not abused; my grandfather made Craftsman-style furniture and cabinetry in the 20s-30s, and I know for certain that a number of his pieces are still around and in use. But buying the kind of quality and craftsmanship that will allow certain products to last for a lifetime is NOT cheap. While expensive doesn't always mean quality, high-quality is almost never inexpensive.