Ask HN: What brand mention tracking service do you use for your startup?

I want to keep track of when people talk about our products online. This includes forums, social media, blogs, and news sites. I feel we are missing out on opportunities to talk with customers and deal with their problems because we find out about them too late (or not at all). For people who are always checking how many times their brand is mentioned online:

- Which service do you use?

- How much money do you have each month for this?

- Have you ever had an important mention get lost?