I don't have a pool anymore, so I can't help you with where to order it from. But I just wanted to add that our pool was Baquacil and we LOVED it. I got so used to it that I cannot force myself into clorine pools at hotels or friends' houses anymore.
We bought ours from a small, privately owned store (that did NOT install pools) in a part of town that was very run down and no one even had a pool!?
I would suggest going to a YMCA or gym where they have a pool and ask where they get theirs. I'm sure they have to buy in bulk, but I'm also sure they know where to get good deals so they can still make a nice profit.