Most consumer web startups have a little video on their website that quickly explains their product. They all seem to be made with the same style. Is there one company producing them all or are there many such studios?
The thing you are paying for most of the time is for someone to beat the shit out of your story to make sure it's as succinct and compelling as possible -- while being 100% jargon free. Whoever you hire, you want to make sure you get that out of the deal if you are paying $$.
They don't necessarily have to come from a company. We hired a freelance animator to create ours which can be seen on Kuhcoon.com. The point of these videos is to explain your product in a way that is easy enough for users of all ages to understand. They are super effective, but can be costly. Luckily I am personal friends with the animator so we got a good deal, but from research I've done these animations typically cost around $300-$500 for every 15 seconds.
At Grumo we specialize on demo videos for startups.
Also if you want to learn how to make them yourself we have an entire animation course at http://grumoschool.com
Cheers!