If you're anything like me you'll have more chemicals in your darkroom than storage bottles. I am always loth to buy photo-chem bottles as (although they are only a few pounds each) buying ten at a time soon adds up and to be honest i'd rather spend that money on film, paper and chemicals. That being said i also don't like using empty water bottles because they feel too thin and flimsy. I recently found a simple solution and that is home brewing shops. Pretty obvious when you think about it - if you make your own beer at home you need something to put it in! Anyway, i found these bottles in a store pretty close to where i live. Theyre 1 ltr, plastic and chemical resistant - exactly what i need. They also do amber glass bottles but only in 500ml unfortunately. Still, can't complain at 60p a bottle! They will post within the UK; if you're outside the UK i'm sure you'll be able to find somewhere near you where you can source home brewing supplies.
Just thought i'd share a quick find with you anyway.