In the UK we don't have such products available from the Supermarkets, but that doesn't really present a problem.

I can get 20Kg grains in food grade buckets direct from the farm online shop and delivered directly. Even 100 Kg or 5x20kg Buckets can be a pain/expense to handle if going down to the supermarket to pick up.

http://www.browfarmonlinestore.co.uk/product-category/milling-gains/

They don't come in Mylar bags but this is easy to do your self using Mylar bags oxygen absorbers etc available from

http://www.fresherpack.co.uk/products/11...old_up_to_20kg/

Smaller individual mylar bags can be created i.e. 2 or 4 kg individual bags of milling grains for bread for 1 weeks use during an emergency. I personally like to also vacuum seal 1 or 2 kg bags of quality Basmati/Arborio/pudding rice or other grains such as barley/steel cut oats/Scotch Broth mixes, dried pulses and beans etc, before sealing in individual Mylar bags together to customize individual buckets for 1 to 2 weeks use. This means I don't have to open all the buckets at the same time and break the mylar seals.

Sealing Mylar isn't really a mystery and will probably outlast the commercial buckets

http://www.youtube.com/watch?v=k_ux2gg0X-s

Edit ... Oh and none of it is contaminated with GMO.