When you run out of somehting you need?
I'm completly out of CA. And I sure as hell not paying $6 a ounce at my LHS. I havn't touched this plane in over a month now(TF Cessna 182). I found a guy online who has 16oz bottles for $33, so I'm picking up a bottle of thin and medium, hopefully last a while.

It may cure in the bottle if you don't take precautions to prevent it.
There is a thread on here that explains how to preserve the CA over time.

[8D]CA is preserved and kept in good condition by storing it in a refrigerator.
I store mine in a refrigerator between building projects and it is always good
to go the next time that I need it (after bringing up to room temp) even
after a year.

store it in the freezer; let it warm up some before pouring.

I keep mine in the freezer and have never let it warm up. There's barely any change in consistency, and stays fresh for just about ever.

I would make sure you know the product and how well it works, some of those good buys are not so good if you can't use it.
I bought some off the net and threw away 3 bottles of the crap. Check out tower if your looking for a larger quanity, so far I have had good luck with it with the exception the med is a little on the thin side.

As a rule I don't let mine set around long enough for it to go bad, but the fridge is the best idea from what I have seen and read, Make sure you seal it up good also.