I've got the model sounds version in my boat with a steam engine noise playing away. Does exactly what it says on the tin, Well, Package. Good sound for such a small unit and very easy to use. Not a bad price either.
http://www.modelsounds.co.uk/As for the sound files you can play any sound on these units as it's basically an MP3 player so you can load the microSD card up with the Spice girls if you wanted a party boat!
The sound files that come from Model sounds are very good though and someone has gone out to record the proper things and then spent hours processing the recordings into a loop suitable for our uses. Personally I think £7.99 is a small price to pay.
Craig.