IMHO, seems like a pretty silly reason to not consider a boat that might be the perfect "one" for you. It's up to you, however. You can demand to talk to the owner, or not. I would..... and I always have. The questions are the same either way. If you want to talk to them and a broker won't facilitate that, then any interest is lost on that boat. Period. It
can be made black and white if you take all the emotion out of it. A lot of people want it both ways.
I would maintain that broker or not price is no issue - IMHO, you should not be looking for a "deal", or you will likely get burned.
You should only ever pay what what the boat is worth
TO YOU, in whatever condition a good surveyor says it is in. Period. Claims of "that is the market" is BS, IMHO. YOU are the market. That may be below the market price or not. May be half of what is asked, or not. 10% broker fee is of no consequence in that equation.
Again, my opinions.