From my experience, getting a loan on a boat slip is not the easiest thing to do (there is a limited pool of lendors). Last time I checked Meredith Village and Laconia Savings were offering them. Usually 25% down with a 10 to 15 year term. Rates are around 2 to 3 points higher than a conventional mortgage.
Maintenance is usually handled by the club (through your association fees and special assesments).
Some slips are listed in MLS, but a good number of sales are private. Usually most clubs have slips for sale posted in their club house, office, etc.
They are taxed as real estate, same rate.
Like all real estate, price is determined by the market (based on size, location, club amenities, etc.). You might want to check this thread
http://www.winnipesaukee.com/forums/...ead.php?t=3773
Like all real estate, location (along with amenities) plays a big part.
As rentals, it is often dificult to make the numbers work from a cash flow perspective, so
appreciation is key. Since you can't depreciate land (IRS), you can usually depreciate part of the purchase as a land improvement, part on the club buildings, etc. That part of it isn't cut and dry. You really need to work the numbers to see if it makes sense.
Hope this helps.