Thank you OP for these. They were very accurately drawn so I lifted the logos to 3D print them in my own stencil template (I have a smaller 3D printer and I also wanted alignment marks at both ends)
For the question above, my slicer software estimates less than £0.50 of filament is required (for reference, yonex stencils seem to be going for £6.99 plus postage at the moment)
I think that the real benefit is the convenience rather than cost eg. If your friend has a Victor racquet to be strung but you only have a yonex stencil then you don’t need to wait a few days for one to be delivered.
The other advantage is customisation. In my case, I started 3D printing them in order to make accurate stencils with custom logos.