Are you looking for any specific domain name and it is not available for the time being, but it could in the future.
it is quite tiresome exercise and almost impossible to check it manually when that domain becomes available. A better solution is to create a bot that keep checking it for you and let you inform when that specific domain is available.
This shared youtube video is a video tutorial by zzBots for this very purpose. In this video zzBot has explained the development/creation of such a bot in easy to follow steps.
