I know this might be random but I have done a lot of research for my wife for sanitary pads. Instead of toxic commercial ones we switched her to natural cotton pads. But cheapest is loblaws for 4.50 for box of 10 Natracare which isn't fully cotton from what I heard. But found one here by Lilian which from what I read is 100% cotton. 14-16 in a pack for 7.99 but got them on a 1+1 sale so it's quite a good deal. Was hard to find information in English since the product info was too complicated for my limited Korean vocab. But found a link here from another site.
http://dp.image-gmkt.com/imageproxy/?src=http%3a%2f%2fwww.bloominghome.co.kr%2fimage%2fsingapore%2fLilianpurecotton_S.jpg&scw=430