Everyone is entitled to their opinion. One guy thinks a new boat is a waste and to buy used; while the next says "for what they want for a 1-2 year old unit, I might as well buy new". Buy local is one mans thought while the next is go buy in the next state over to save a buck.......I'm not going to say one is wrong and one isn't, I've done it all. I've bought used instead of new, I've bought new, I've bought out of state, and again locally. With that said, here's my opinion FWIW;
Find the boat you want, check a couple of dealerships, find one you want to work with and think you can be happy with and move forward with your new rig. I like to support my local business when appropriate however I won't buy local if the only choice is poor service or getting completely fleeced. Spending a little more to have a local dealer in my corner, convenient service (assuming its decent) and to keep my money at home, I have absolutely no problem with. the cost of doing business is different in different places.
Is there room to negotiate on a boat, well this is a bit of a loaded question. It's like asking the same about a car and it comes down to the dealership and how they have there prices structured. Are they a best price place where it is what it is, do they inflate the prices a little so they have some room to negotiate or do they simply advertise msrp and work down from there? Again, not a right or wrong way, the only thing you can do is check the pricing at a few places (make sure it's apples to apples right down to options and accessories), weigh the pricing with services and convince and select your dealership based on your how you value those things. Two different people are going to have two different ways of looking at what some of those factors are worth to them.