I guess it's better to buy domains from a famous or widely known domain server with good reputation. I used name.com and Yahoo, both are okay. I prefer Yahoo actually, and I also use their hosting service, the reason, Yahoo is quite famous website for sure, and I've been using Yahoo mail, Yahoo messenger for quite long, I also feel like paying something to Yahoo as a returned favour. :) The price is quite similar among majority of the domain servers, which is about 10$ per year for a .com domain.