Just an update: I spoke to the dealer, told him that I did some research on the '84 V20 and asked him his opinion as to what the price should be. Without hesitation he said about $3800 to $4000 - which is exactly what most everyone here said is the right price. I guess boat there still are honest boat dealers around!
Anyway, he said he would give the offer to the owner and see if he accepts it.
Stay tuned...
Have a great weekend