I use ID11 for my film. After mixing it is stored in DARK brown glass bottles and never seems to go off even over 6 months in a partially full bottle. Paper developer I buy in 5 litre cannisters (Ilford Multigrade) and decant out again into glass bottles and that also never goes off (5 litres lasts me approx 2ys-18 months). For the main storage I use 500ml bottles which cost approx 35p from Boots Pharmacy and then decant the contents into 100 cc bottles also from boots. I also use old screwtop brown glass wine bottles with the added benefit of HAVING to consume the contents beforehand!

Concertina bottles are about the worst thing to store developer in. The plastic is so thin it is gas permeable and the contents will oxydise in quite a short time. OK for things like fixer and stop bath but never developer