Most of what I print on right now is 8x10 and most of what I shoot is 35mm so a couple of years ago I started cutting the 8x10 down to 7x10 for a perfect (almost) fit. Doing this I of course end up with a box of 1x10" test strips and I never used them all. I used to just tear up a piece of paper if I needed to do a test. I guess I save a few sheets a box this way although it wasn't really my intent. I think I make more test strips now than I used to. I have noticed that. Back in the day I never made test strips, I just eenie meenied the exposure and contrast.
Yes paper is getting expensive unfortunately. At least it is still available. The way I look at it though is I have the best equipment of my life, the most knowledge I have ever had, am probably printing better than I ever have and it is a lot cheaper than me going through the computer even though I know how to do that too. You just can't beat a silver print. There is nothing else like it.