If you are aiming for TechCrunch or Mashable the best bet would be to give them the exclusive of the launch of your company or perhaps a feature launch. The latter might be a little weak but still worth a shot.
Nowadays the internet has made everything more transparent. With this in mind you may want to research and see which reporters are excited about your industry. You could engage with them on Twitter or comment on some of their articles to gain their attention.
As a recommendation I would stay away from PR agencias in the event you are very early stage.