I see the assembly police have arrived, joking Mariusz . I do agree. A koshirae done badly is a waste of money and time, some may say a koshirae done well is still a waste of money and time , keep the original shirasaya!. Parts can be difficult to come by, it can take years. As for pricing, there are traditionally trained craftsman who are reasonable, allthough expect to be in a que for a while. Wanting a blade in koshirae is down to ones own taste, the blade can still be appreciated. If the parts are correct, the rest of the work is traditional and authentic, what harm can it do, besides blow a huge hole in your pocket.
Alex.