There are a number of sources for good quality CA. But not all CA is created equal. Terms like "medium" are relative. Some medium is thicker than others.
I have also noticed that the acceleration factor is different from brand to brand. For example, I had some CA from a local hobby shop that I apply with paper towels. It is well known that paper towels act as a mild accelerant. When I ran out of the hobby store CA I got some through the bulk buy that Daniel put together. The quality is great, but it reacts stronger and quicker with the paper towels. I have to fold the paper towel thicker to keep from burning my fingers (or gluing them together;-).
The key is to experiment if you change brands and adjust to the characteristics of what you are using.
Personally, once you find a brand you like, I would stick with it rather than shopping for the lowest price.