Mark
Hi!
That's a very cool mod! Must ask you how much Prevision charged you for it, approximately.
Yes, the cost will be around the same as a 2.8F, if:
a) you don't already have a camera
b) you don't already have a Maxwell IntenScreen
c) you don't already own the Hassy prisms, finders, etc.
However, if you do, then the cost will be the labor costs & materials for building the bracket.
Plus
d) Hassy parts are much more available than Rollei parts and so
e) cheaper these days. Can't even find a copy of the Rollei rigid chimney finder, for any price. The Hassy one was $50.
Chris