I suspect the chemicals were shipped from the manufacturer in light reducing containers because the containers would likely sit on an open shelf at the dealers'. I think that keeping the chemicals in a cabinet would protect them from light regardless of the type of container.
From my personal experience, not a scientific test, I have come to believe that a glass container keeps chemicals longer than a plastic one, even if not full. I've read that many kinds of plastic will breathe oxygen, and since the outside surface of the container is relatively large, it allows chemicals to oxidize more rapidly.
I believe that www.specialtybottle.com has amber boston rounds with teflon caps.
Not sure how the prices compare though..
I use plastic fizzy drink bottles on the basis that if they keep CO2 in, they should keep O2 out (even allowing that the CO2 molecule is larger than the O2 one...). However, a lot of air is diffused in the water anyway (about 5mg per litre in houshold drinking water) so it seems you are locking the enemy in there with the chemicals anyway....
I use white plastic jugs for chemical storage. When not in use the jugs are stored in a closed cabinet; which means light can't get to the jugs. So far no problems doing this and it is cheap and I'm recycling.