We bought an AIS transceiver for our Raymarine C80 plotter and we are very pleased. We got the same unit that is West Marine branded ($500) but was being sold directly by a company called Cactus Marine who imported them from England where they are made. We got it at the Annapolis show and don't remember the price but it was a lot less than $500 and is a transceiver.
Install went fine. It requires a particular baud rate setting on the chartplotter and that might be a problem if you are sending data at other rates to other devices because it seemed to me that you could only have one baud rate sent - but I willingly admit to not being an expert about electronics.
Back in the water in Grenada - with new main and #2 and cockpit canvas (Santa came early). Will spend the winter and early spring in the Caribbean and then head to Bermuda and the northeast US. Still trying to decide if we will bring the boat to Canada, either in 2015 or 2016.