I would buy at least 2, maybe up to 4, but I don't know if you would be able to get the scale you are looking for.
I looked at the knife you suggested, which got me looking in a new direction.
The Richmond Laser Petty looks a lot like that yanagiba-ko you recommended, but you made it with the AEB-L. It is the right size I'm looking for and uses a steel that i prefer. Plus the thinness is attractive.http://www.chefknivestogo.com/rila18pe.html
I think I'm sold on that one, and maybe pick up the Richmond boning knife as well. Well, sold for x-mas at least.