Theres some good information here - I've been digging out some facts and it seems that cotton bags are much more 'costly' to the environment than plastic but I wonder if this takes into account the fact that a cotton bag can be used about 100 times so 1 cotton bag = 100 plastic bag rather than 1 = 1.
It's easy to make bags out of old curtain fabric etc which can be picked up for a few pence in charity shops.So there is no need to buy new cotton bags and maybe its not really appropriate for us to be selling them? Also mostly they are made in China and imported to the UK.
Paper bags given out by shops like Primark can be made using virgin paper pulp rather than recycled paper but they do biodegrade.
Anyway look at the site and you'll discover more
Earth Resource Foundation