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 $$.

You can see examples of videos our team has done along those lines over at http://whatnowexactly.com/

And to answer the style question - there are probably 10 good companies in the U.S. that do these sorts of videos and we all know one another ;)