Domains names as i simply defined in my previous post are name address of a website on the internet. And an extension is also what make up a domain name. Try searching a website with a web browser without adding .com, .ng, .com.ng or any other top level domain, instead of being directed to the website or blog, you will be directed to a search engine, giving result for that search. Examples of Domain names are .com, .net, .org e.t.c. but the listed domain names are international domain names and can be bought from domain registrar companies like godaddy,which most of this international domain names are costly or expensive. Although some local country domains are not cheap, more expensive than some international domains, Example is .Ng domain which is about 8,000 naira, but it is a Nigerian domain.
Now answering your question, You might have asked where can you get a .com.ng domain for a cheap price, where can i get a .com.ng domain for free, which domain registrar registers a .com.ng domain in Nigeria or List of domain companies that has .com.ng domain at a cheap rate in Nigeria.
List of Domain Registrar Company to Buy a .com.ng Domain in Nigeria.
There are so many more but i hope you can pick from the domain listed above