In my search for a standalone AIS unit (and me being a cheap sucker) I looked into Miltech marine. They have just introduced what they're calling their "collision avoidance system"

http://www.milltechmarine.com/products_watchmate.htm

It's currently $499. That's the actual unit that you see on that page. You have to team it up with an AIS receiver and a GPS.

Miltech offers the Smart Radio SR161 and the Smart Radio SR162 AND the Smart Radio SR162G AIS Receiver, note the "G" in the name of the last one. That stands for GPS, meaning that the AIS receiver has a GPS receiver built-in, you don't have to have another unit. THAT means that the whole shebang functions as a simple nav station GPS as well as AIS. The SR162G sells for $499....

SR161 is a single band monitor, that switches between monitoring the A and B AIS bands....decides where it's getting the best signal, and that's what it reports to the rest of the system.

SR162 is a dual band monitor....it monitors and reports data from both A and B AIS bands.

SR162-G is the same as the 162, with a GPS in it.

Thus $1000 for the lot with a SR162G, or about $780 for the SR161 single-AIS band plus the Collision Avoidance System.

It's rather more expensive than the NASA unit, but then Miltech is in Washington State, and you can call them up directly for tech support. I called them last night and they were really helpful. The guy I talked to knew about the SSS and the Singlehanded TransPac.