Personally, for $150 approx, I would get me any of the following:
- Yashica Minster
- Any of the Yashica Lynx models, especially the 14 or 1000
- Yashica GSN
- Konica Auto S2 (or S3)
- One of the better Minolta Hi Matics
- Canon QL 17
That is, any of the "common" but excellent fixed lens RFs that one can get for $1.00 to, say, $50.00 in "decent" condition, of which there are many to choose, then send it off to Mark Hamma to have it repaired/CLA's for roughly the same total amount.
A camera from the mid? early? 60's - even if in "mint" condition will be in need of servicing regardless of cosmetic condition. While I'm sure the Mamiya is a fine fixed lens RF, they're all pretty much in the same league in terms of quality, all having the same construction essentially (except the GSN due to its stepless electronic shutter), same 6 element/4 group (7 element, 5 group for the Lynx 14) high quality coated lenses...
For $150, a Konica Auto S2, GSN, Lynx, Himatic for as cheaply and in as good condition to start that you can find... then off to Hamma. Another problem with the "rarer" cameras is there are no parts for them. But a GSN? A Konica Auto S2? Buy a "parts" camera - or two or three...