I bought one of these for my boat from Birdsall Marine. These gys have take the traditional flourescent lgiht housing found on many t-top lights and have a insert or you can buy the complete rig.
They also have them in diferent color combos which is pretty cool.
Those Birdsall overhead t-top lights are nice. We sell some nearly identical lights from Sea Master. The ones we sell can actually fit right into a spot where an incandescent bulb was. http://www.seamasterlights.com/productlist.asp
I am a huge fan of everything Birdsall makes. They'll be on my comp list for these lights once we start shipping, that's for sure!
The price will be around $100. We're already set on that. Development is coming along well and we're still on schedule. Once we cut the molds for the housings there is no going back, so we've been checking and double checking to make sure the housings are attractive and functional. We're still looking to release these in march.
The underwater lights on my boat are the Abyss S1515's. They are very similar in light output and mounting style to the Ocean LED A12 Amphibians. Both are on our site.