fleschler, I didn't know they were in abundance; that explains the relatively cheap price. Since I have several pieces of equipment that can use them I will stock up.
We have a tendency to think more expensive things sound better; I needed a 12AU7 and found one that didn't have the brand on it; just 12AU7 made in the USA. I put it in and was shocked at how good it sounded, I believe it sounded as good as a NOS Mullard, which costs much more.
If we judge by the audio alone, as opposed to the name, we can save a lot of money.