What you have invested has nothing to do with the current market value of your boat. What buyers are willing to pay at this time will determine what you can get for your boat.
Here's how I did it with my Catalina 22 that I sold. First of all, contact the county tax office and see what the tax value of the boat, motor, and trailer is. Then go to BUC and NADA and get the values there. Next, go to every site that you can find that lists sailboats for sale and see what the asking price is for other boats of same type (brand and model). Plot the results with year of the boat on one scale and asking price on the other. Through this plot of points, draw a straight
line that appears to be the mid point (average) of the various prices. Now, look at your year model and see where it falls on the plot. Now, you have an average asking price. Most sellers will have about 10-15% included for negotiating room....i.e. they will take that amount less than the asking price. Now, you have your price. If your boat is really top notch, you can add a little to that.
At this point, you have a boat with proper asking price and a negotiating allowance of 10-15% to move the boat. This makes you equal with all the other Oday 22's, many of which have been hanging around for a long time waiting for a buyer. Really want to move the boat? You've got to make your boat to instantly appear to be a great buy to the potential buyers. Lower your asking price another 10%. Put up web site showing pictures, lot's of pictures. Keep the boat clean with fresh bottom
paint and waxed. Highlight all the installed equipment that goes with it and include all the equipment that the buyer will need...lines,
anchor,
radio, life jackets, mops, brushes, etc. List the boat on lots of web sites. Place the boat in a high visability area where boaters are likely to pass by. Don't do these things, and you may be waiting a long time to sell your boat.
As to what you paid vs. market value, look at the housing situation. To get a house in CA in 2004-2005, you might have paid 450K for a modest house that in today's market, sells for 150K. As I said before, it's what the potential buyer is willing to pay, not what you would like to get.
Good luck in moving the boat.