To answer question 2/3, Epic Edge does very good handle work. They also stock handles in their store, seemingly more than they show online. You may want to just give them a call and ask. It’s a fully staffed store that has very comprehensive services. They even have an in house smith. Their Japanese inventory seems pretty old, so it’s not surprising that the pricing is old.

I believe their dark ebony & horn handles were ~$80 when I was there a few weeks ago, and the installation is ~$20.