There is the DIY option for those with workshop access or capabilities.
Choose one of the high quality pro lens systems which had leaf shutter lenses.
Used ones are falling in price.
All the technology and image quality is in the lens.
From my searches, and as others are mentioning in this thread, used pro bodies are risky and costly, whereas used lenses are available for reasonable prices and in EX condition.
I chose a Pentax 6X7 90mm ls
The make a camera to suit.
(I put a thread on the Camera Building section, there are others doing this too, making cameras a lot smarter than mine)
I became really interested in this as a hobby and preparing to make another one, taking advice on the way