Maxim, to put you in the ballpark, I''d describe your issues to be...
1. Does Westerbeke still support the engine with parts? (Call them to find out)
2. If not, what level of remaining supply is there among parts suppliers - e.g. you might call TransAtlantic Diesel and ask them.
3. 3200 hours can be a lot for a diesel, tho'' many carry on for double that time or even a bit more. It depends on how well it''s been cared for (over its entire life, not just while in the hands of the last caring owner), how it''s been used, etc. I would definitely survey the engine along with the boat, if you get to that point. Over-temp, low compression, etc. issues - deservedly - would lend weight to your requesting a price adjustment.
My impression is the Westerbeke was (and mostly still is) an old-time New England firm with strong technical competencies but conventional manufacturing and marketing behaviors. They have been dragged into more modern methods due to heavy competition but have successfully responded with a healthy line of products. OTOH the ''75 model, like my ''79, is probably a low-rpm, heavy, now probably not supported beast of limited further life. You''ll need to think of this when considering the purchase.