Anyone here into Domain buying and selling business?

[debasis]

well, it's hard to find a buyer to your domain name.
And we have risk to do this because we need to buy the domain name first, so we use our own money first.

Well if you are developing website initially you need a domain name for your site for sure and only if your site gets more visitors then even you domain will be come more in demand

Well, if you make a site on a domain, then you're selling website not a domain.

Depends as if i don't want to sell my concepts and the domain is very catchy, i can just sell my domain without my website also

yes you are absolutely right one can either sell his/her domain or sell his/her whole site or it also possible that he/she can sell his database or content only.
Take the example of a forum called SOP one guy purchased the database from this forum and the owner charged a lot from him and purchased a bike.
Thanks.