Nest – a 'crazy idea' at a crazy price?

What kind of business could you buy for $3.2bn – or about £2bn? Well, in the UK you could pick up the construction giant Balfour Beatty, which employs more than 10,000 people, or the only remaining High Street electronics chain Dixons, with a workforce of more than 30,000. Or, if you are Google, that is what you can pay for a tiny connected home business employing just 300 people.