Which stereo were you quoted on? I recently purchased a vista complete with the Spaudio Cast system. I paid a little bit more than $1,800. I was quite apprehensive on spending a couple of grand on a stereo for a spa. I mean two grand can buy a hell of a good home stereo...
Anyways we spent the money and we don't regret it at all... The transducers are totally awesome. I've never experienced surround sound like this. Sitting in the tub and having (feeling) the music in the water. Your whole body hears the music not just your ears. Everyone that has used the tub is quite impressed...
Another great feature is that most of the sound it limited to the tub. By this I mean you can crank the volume without disturbing the neighbors...
The system also comes with a couple external speakers. The transducers can't produce any high end frequencies so the external speakers are a must...
Over all the system is expensive and only comes with a one year warranty, however, I can't imagine a better system for a spa and definitely don't regret purchasing it...
Good luck with your purchase
Jimmy