Hi,
This sounds like a fantastic project. Having worked on games like Battlefield I have in depth knowledge of game trailers and also Film and TV animation.
Although the example you've supplied isn't of the highest standard compared to some of the top trailers it still takes a long time to create something with that much detail. Most high trailers cost around 100,000 - 300,000 dollars to make. For a short film at the level you've provided the cost would be around $50,000.
I hope this doesn't put you off but thought it worth mentioning as you may be disappointed with the results, if you go for a cheap option.
Kind regards,
Peter