Thats Kind Tetra - But Uk and European folk really can get them for less than your postage.
It's just knowing "where" to get them.
UK - Most independant gorcery (fruit and veg) stores you can grab a few for free.
If you have to buy them - go to Tescos - they've got all sorts - and the slightly thicker ones (which i think are better for removing humidity). It will cost you about £1 for 20 and they're bigger than the gorcery store ones (which means less bags to shake lol)
Hope this helps some UKers find their brown bags lol
Primark bags are ideal nice thick double layer of paper