I saw many people had their own website to sell photos. Is it worthwhile to do that ?

I guess it depends on your content. If you only shoot microstock, it's overkill and you can suffice with a simple site with samples. But if you do a lot of specialized editorial or assignments/weddings/events and you have a large personal network, it's the way to go if you don't want to email at every inquiry. For instance, for weddings, you can keep the gallery private and issue the people involved with a password.