Yes - besides NASA, Comar and EasyAIS are available in the UK. The Sitex one available in USA is a rebadged NASA. Also a newish one from an outfit called Milltech.
The only real difference between any of them is whether they have 2 actual receiver circuits for the 2 AIS channels or switch channels on one receiver.
In addition, now that Class B ('leisure') AIS is on the go, the later ones from NASA are now class B compatible. (If anyone has an older NASA unit, you can ask them for a replacement chip. They'll send you one on receipt of the old one.) Comar also now have a Class B transponder (around £600). Maybe worthwhile looking at if you do a lot of cross-channel / Irish Sea.
I don't think any of them are waterproof, so on a RIB would need mounting inside a console, possibly inside a box!
A lot more chartplotters now haev AIS facility although be aware that many only have one suitable port. Not a problem until you want to connect another NMEA device. Multiplexers are available, but not cheap.