Do a google search on "Stock Music". There are 1,001 websites out there that sell stock (royalty free) music in a billion styles and configurations.

This is how we buy music for our videos. We get an edit completed to the point where we have a "feel" for the scene. We then watch and listen to different samples (for free) online, and make decisions what we like - what works for different scenes. Just takes a TON of time to find the right sound and feel for a particular scene.