Been Sitting...

How was the boat stored?  Were the cylinders fogged before it was put up?  Was the carb drained of gas before it was put up for storage?  If not, a carb rebuild will probably be in order.  Was it in storage or outside uncovered all this time?  Can you put a wrench on it to see if you can move the cylinders?  The impeller is most likely dry rotted and will definitely need replaced at the very min.  Was the lower unit stored with fresh oil, drained, or just put away with old oil that might have had water in it? 
 
To be safe and if you truly want to get the most money out of it, I'd take it to a qualified repair shop and have them check out the motor and get it running.  Once you get it running properly, check out NADA dot com to get a ballpark figure for asking price.
 
If it was stored properly, you probably won't have too much into it to get it up and running.  If it wasn't stored properly, you may want to just put a low asking price on it (refer to NADA again and go well below) and state "as is" in the ad and tell whoever looks at it that it is being let go as is and buyer beware. 
 
Personally, unless it is practically being given away, I'll never buy a used boat at close to NADA retail unless I take it for a test ride and if it is a big enough purchase, have a marine survey done on the entire boat. 

Thanks for the info, selling as is was what I was thinking also.
 
I bought the boat while single and in the USAF stationed in California. Got transfered to Arkansas, got married, and got back into fly fishing. The kids came along, and it just got pushed to the back burner. Now, it is a out of sight out of mind thing. The boat is sitting in my in laws back yard, an hour from where I live.
 
It has been covered and tarped the whole time. Unfortunately, due to my stupidity, it was just parked. I used to keep the batteries charged, and turn it over every now & then, but other than that, just parked.
 
Bulldog, you sound like my wife!!