Each manufacturers have several lines of speakers...from low end to their top shelf equipments. I agree with the statement that you get what you pay for...and some of us are finding out, that you can, once in a while, buy top end equipment for a very reasonable price. Recently, a friend of mine was updating his tv and bought a home theater in a box. He and I had heated argument...sic discussion about the quality of such set versus higher end stereo equipment. Finally, upon my insistence, he sat and demoed one of these theater set versus a home theater in a box. He said it was night and day.
When you are dealing with sounds for a boat, there are some distinctive challenges. First of all, there is an open space to project the sound. You are going to need a lot of power..and that mean amps. The second is you need speakers that are going to handle the power. Lastly, the construction of the material in the speakers are what makes the price difference. Cheaper material mean inexpensive speakers. I would akin trying to equip a boat the same as trying to equip a convertible.