There is an old-fashioned parchment maker in upstate NY in the Hudson Valley who still makes it the old way – soaked in lime, hand stretched on metal framed, had scraped, and hand-prepared even before it goes into the lime bath. I have NEVER worked with such amazing quality parchment before. Since it is all hand done, they can often make it to-order, so I can choose the size, dimensions, and thickness of the piece, and can even get it surfaced for writing on both sides. They do cow, sheep, goat, and occasionally deer and buffalo skins. Unfortunately, they are not Jewish, so I only buy from them for when I’m writing non-kisvei kodesh (In addition to megilos, I write and illustrate kesubos, custom bentchers, haggados, and other art-pieces).
The place is called Pergemena. Check them out online.