Nenad,
The problem is finding it already woven into a neat strap withour trying to bind edges etc.... which don't hold up well or look neat.

Yes, one could have anything made to order but cost is an issue. Even buying a standard size as I do subjects me to a minimum length which is a LOT of linen. Remember, we are serving a very small market here. Even my minimum on a standard size lasts me 6 to 9 months and I make a lot of strops.
To have a mill setup for a certain specialty would require thousands of yards to be purchased.

Tony