Yamaha makes a decent product and is not over priced for what you get. However you should give a listen to other brands in the same price range. You can also look at used speakers this way you get a better brand for less.
Best speaker yamaha ever made was NS-1000 and NS-1000M. They have berylium mid and tweeter and 12 inches woofer. I am lucky enough to have 6 NS-1000 in my HT system with Rotel Components and Amps. You can find ns-1000 on ebay for arround 1500. It is a good alternative to new speaker.