I've never heard the LS50W described as sounding that way. I wonder if there was a problem with that speaker, a poor quality source, etc., but there are plenty of other great options out there and it sounds like you have some you're excited about...pick what sounds great to your ears and best of luck.
You definitely aren't obligated to buy from your local dealer, but if you're buying something they offer, I think it's a good idea once you've worked with them to at least make a phone call as a courtesy and see if they can match the price you can get online or elsewhere...many times they will get far closer than you expect and you'll have the benefit of someone local to deal with any issues down the line. They'll appreciate getting the chance to earn your business and most are very understanding that you buy elsewhere when they can't come close on the price...and if they're a total jerk about it, you know you're better spending elsewhere anyway.
You definitely aren't obligated to buy from your local dealer, but if you're buying something they offer, I think it's a good idea once you've worked with them to at least make a phone call as a courtesy and see if they can match the price you can get online or elsewhere...many times they will get far closer than you expect and you'll have the benefit of someone local to deal with any issues down the line. They'll appreciate getting the chance to earn your business and most are very understanding that you buy elsewhere when they can't come close on the price...and if they're a total jerk about it, you know you're better spending elsewhere anyway.