We did a comparison of domain names pricing of top domain registrars (NameCheap,GoDaddy,1and1 and ResellerClub) The results that we got is among the 4 ResellerClub offer domains in a cheaper price compare to the other 3 and ResellerClub does have more domain names extensions to choose from.
I highly recommend ResellerClub as they are really affordable compare to other top domain registrar.