Thanks for the comments whowantstoast, the Koni-omega prices look good for this type of project.
The reason for choosing good quality but lower cost lenses is not only to keep the cost down.
The lenses have to spend time in the workshop where there is dust and metal chips etc, during the build of the bayonet mounts etc.
So far I have been careful, and have no damage , but there is a risk that the lens will be damaged.
So I would not try to use an expensive MF or LF lens on these projects
By now I am well into the Takumar lenses, i have 3 and also a Computar variable focal 105~150mm out of a 70mm long -roll camera.