I got them at an online retailer. Extreme discount. I took a gamble as I thought it might not actually be linen at the price. Especially wide enough to make sheets. Don’t forget it shrinks.

Worthwhile going to a store to feel all what’s available, different weights, weaves etc. There might be a clothing or upholstery oriented place that has more useful. For textile-industry, do not expect meaningful online presences. A lot of fabric stores have a website from 1997. A few 200px photos of stacks of fabric, a list of random brand names, a phone number and an address. Call them and tell them you are interested in linen for drapery, sheets & upholstery and they will tell you if have have that kind of thing and if not where to go. But it is a touch and feel business so actually going is better.

Also the word “linen” is used to mean a lot of things. some of which contain no linen. you want “100% linen” and knowing about weights will help https://www.onlinefabricstore.com/makersmill/linen-fabric-product-guide/