Scale Hobbyist, which I find usually has the lowest price for almost anything, lists these for $42. They also have the shorter section with steps descending to water level for $27. If you live in New England, you often get next day delivery for their regular shipping price. I have several sections of these, and as I recall the track is a correct 41 mm for 1:35 SG.
http://www.scalehobbyist.com/manufacturers/Italeri_Models/Buildings/browse.php?s=0&t=6&man=itlActually, the only thing new is their packing two of them in a single box.
There's no reason they couldn't be built back to back, but you'd have to create a convincing end facade. I agree that they're perhaps more appropriate for an industrial dio than a nautical scene. It could be really impressive with a gantry crane doing a road or rail to ship transfer (perhaps with the load in mid-air, and the ship not modeled), but it would be a scratch build. You could probably use structural castings from relatively inexpensive O-scale truss bridge kits, or even this Walthers HO scale bridge crane:
CMK has a kit for a steam harbor crane, but I've never cared for the look of it - I think mostly because they represent the crane boom as a solid structure, with pseudo-lattice work cast on the side. It would be expensive, but you could keep the cabin and build a new boom, although it would be relatively easy to scratch something similar.
I checked to see if anything might be available in the British 7mm model railroad scale (1:43.5), but no luck.
Here's a Marklin HO scale digitally controlled gantry crane:
http://www.hobbylinc.com/htm/mar/mar76515.htmA skilled modeler might be able to build a larger superstructure around the mechanism, but it would be an expensive risk.
If you do want something in the water, a barge would be easier to fit and perhaps more typical. Something like an LCM hull could be a possible starting point. Some were converted to ferries after the war, and an aggregate barge with the ramp welded closed might be reasonable - perhaps a railway wagon dumping coal into it. Maybe something along these lines:
I found what looks like a good article on various types of cranes here:
http://myweb.tiscali.co.uk/gansg/9-loads/11-crane.htmCharles
Campaigns Administrator
) the Graf Spee in 1/35th though? 
