I bought a tube of "Geneva Foundation Layer Canvas Stain". I rate it 5 out of 5 stars. Here is why:
As I do not usually like to buy items off the internet, I was somewhat hesitant to purpose it (dislike returning items from the Internet), but I am very glad I did. Per Mark's video, you will quickly see that it covers very well and thus I believe a tube used correctly will last a long time. Plus, your stain will be the same color every time. As mentioned in a previous conversation, to get rid of streaks, I use a fan brush (which I have stopped using for painting) as it gives a nice smooth and even coverage. A fan brush will also help in using less of the stain. Thus making the stain more cost effective.
If you are a follower of Mark's advice, and you want to do your paintings "right" from the beginning, use Geneva's canvas stain.