Here's a YW search for Western Europe with your parameters (to 35 feet and $15K US):
(Sail) Cruiser Boats For Sale Belgium
And the same for the Eastern US....
(Sail) Cruiser Boats For Sale
Obviously a huge difference in selection, but at that budget not a lot of typical serious ocean going boats will pop up.
You're going to need patience, diligence and a bit of luck, I suspect, to find the perfect example.