Domain names can be purchased from a few dollars to a few dozen dollars, depending on the type of domain. To understand more about the different types of domains, read here.
Some popular domain name registrars include:
Godaddy – https://godaddy.com/
NameCheap – https://www.namecheap.com/
Netfirms – https://www.netfirms.com/
Name.com – http://www.name.com/
Domain Name Forums
There are a number of popular forums that specialize in domain name discussions.
NamePros – https://www.namepros.com/
DNForum – http://www.dnforum.com/
DomainState – http://www.domainstate.com/
To find some of the support forums of domain registrars:
NameCheap Forum – https://community.namecheap.com/forums/
Dynadot Forum – https://www.dynadot.com/community/forums/