Compostable or Degradable Bags

So we can now source compostable or degradable bin liners but can anyone tell me where to purchase suitable replacements for the likes of freezer bags and the more solid zip lock bags. I have taken to using a lot more containers to freeze food in, but sometimes one needs a "plastic bag" and I am refusing to buy any more plastic ones.

Best solution i've found so far: www.stonepaper.co.nz/rich-mineral-bags
however they are a bit difficult to come by unless you want to by a couple thousand....