On my last visit to Brittany, some time ago now, 1 found what I was looking for, really fine and large embroidered linen sheets and plenty of very rough (porage look) hemp sheets. Since my previous visit in 2008, both had become extremely difficult to locate - so, in a way, as I had to travel 100s of kilometres, stay in a lot of different areas to be there for early opening times of the Fairs, you could say that was quite hard work - but to me, the thrill of the chase is still there every time I walk through the gates and wave my trade card to get in for free. When I gag at the new higher prices, there is always a good excuse - it is too late in the season and the best has gone, you cannot replace good stuff during the summer months because everyone's stock is so low - even ordinary plain linen sheets with minimum drawn thread borders are hard to find in good condition and no one wants worn out stuff or small sizes. So you have to be persistent and dig deep!
In fact I came across one huge stall where everything , in great white heaps, in white cotton and linen, clothing and bed and table linen, was priced at 10 Euros per item, or less - but every single item was a reject and I was told this dealer buys it all by weight from all the other linen ladies who are pleased to get rid of very unsaleable items. But if you sew and design, this is a good cheap source and you might find interesting costume, underwear, lace to re-use and hand embroidered borders if you love to '
chiner' i.e. trawl the markets. You need time and luck.