Moving the enlarger is a real pain, either to get to the wall or the floor. And as Nicholas says, the facing wall is too far away, although I guess I could stuff the 150 lens back in it and try if I get desperate. (In a next life the enlarger is going to be mounted on a drop-bed table and arranged so that it's easy to project on the wall, but that's a project for next decade.)
I really thought I'd find a cheap lens on eBay, but not so yet. There must be a million 50mm and longer. And I was a little shocked by the Orion lens for the FEDs. That was my first scheme; buy an old Orion and use it with both the FED and the enlarger. But someone must have told these guys that they're really decent lenses, and they want an arm and a leg for them now. I can find new in the box 25mm enlarger lenses cheaper than they want for an m39 Orion-15.
There are a couple of m42 28mm lenses that aren't bad that I'll watch. I'd have to make a new lens board for that, since mine are m39, not M-42, and I'm not going to hack them up for this. But as pointed out, a small piece of wood and some flat black paint works wonders. And an m42 to Contax/Yashica adapter flange would work perfectly for a retaining ring.
But an inexpensively priced decent enlarger lens that I can put on a board and leave in the darkroom is the ultimate goal.