What's a simple, cost effective way to get good soundtrack for political or educational videos?
There are a bunch of free stock music sites out there. You tend to get what you pay for, and it would probably behoove you to learn how to edit music a little bit since you'll always have to cut these cues down to suit your actual purposes.
The limitations of the "totally free" route are pretty obvious most of the time. Limited selection, mediocre production quality typically, and - if you're working for an organization that cares about stuff like this - typically no guarantees of any kind that you're not actually violating anyone's copyright.
The next step up from this would be relatively inexpensive paid royalty free sites. They have a wider selection, more legal security, and usually much better search features and UI's
Here's one people like a lot:
And then even higher up the budget/quality spectrum, are proper license library and music publishing/production companies like two I used to work for:
These are a lot more expensive, but typically have actual Music Supervisors and composers in house who can help you pick excellent tracks and even have custom music produced for you. Additionally, because these are license libraries, they typically offer a range of different licensing options - from the limited use to unlimited use, which vary widely on price
Shutterstock and Getty also have libraries of Royalty Free music that you can search through. Getty is always stupid expensive though, and their licenses tend to be highly restrictive.
Alternatively, of course, you could always hire me or one of my composer friends to write an original track!