Unfortunately the terms "cheap" and "digital back" don't seem to go together. :( You could mod a 10 year old old Hasselblad/Mamiya/? 6x6 back onto a Holga but

Unfortunately the terms "cheap" and "digital back" don't seem to go together. :( You could mod a 10 year old old Hasselblad/Mamiya/? 6x6 back onto a Holga but even those backs are still worth plenty of $ I think. Enough that you'd want a Hasselblad or a Mamiya to go with them. Lot of trouble when 'Hipstamatic' is $5 or so. ;). That said, I'd love to build a digital rangefinder camera from a 70s era rangefinder. If anyone has links to any successful frankencameras of this kind, I'd love to see them.