Sounds like you are looking at an AIS receive/transmit system. When I said cheap, I was referring to the receive only units.
You can get into a low-end Radar only for a lot less than $3k these days. Make it a radar chart plotter, 4kw, etc then the price goes way up. A Furuno 2kw unit with a 6in B&W LCD display is around $1,350. The radar install is more time consuming. Given where you sail and your plans, radar would be nice.