Chesapeake,
I'm certainly no model for negotiations, but $8300 seems too high for a boat with a "blown powerhead" ;) (use those words)
Tell him you've consulted a yamaha mechanic and the compression results indicate that the power needs to be rebuilt.
If he says that it's just a head gasket tell him what seakindly said "if it was just a head gasket you'd have already fixed the problem"
Tell him that your still interested in the boat if he's willing to drop the price significantly to reflect the blown powerhead and you'd like him to recalculate the price based on the average price of a rebuilt powerhead (including labor).
From iboats:
http://www.boatmotors.com/motorparts...disp=&cyl=
endor 107 :
HP CYL Description Price Core **S&H Subtotal
150-200 V6 Rebuilt, Rebuilt $3625.00 $400.00 Call Us $4025.00 View
Vendor 2 : For over 17 years we have been dedicated to providing our dealer network with the highest quality sterndrive and outboard components known in the industry.
HP CYL Description Price Core **S&H Subtotal
200 6 Rebuilt $3047.06 $500.00 $136 $3683.56 View
200 6 Rebuilt, Prov200 $3047.06 $500.00 $136 $3683.56 View
Vendor 3 : After 17 years of continual growth, we have achieved recognition in the industry for excellence in quality of workmanship and product integrity.
HP CYL Description Price Core **S&H Subtotal
200 V6 Rebuilt, 3.544 bore, 4 post, large crank $3432.19 $750.00 Free $4182.19 View
Vendor 4 : After more than 10 years supplying marine customers with more than 50,000 high-quality remanufactured engines we have become a world leader in two-stroke engine remanufacturing
HP CYL Description Price Core **S&H Subtotal
175-200 V6 Rebuilt $3373.75 Core First Free $3373.75 View
200 V6 Rebuilt $3373.75 Core First Free $3373.75 View