What are some good sites to get assets from other than the Marketplace?

I would check out Mixamo for animations, they have a fairly large collection and they can easily be imported and retargeted in UE4. There are likely many more sites out there, but I will let others fill you in since I am at best a novice animator. :wink:

If you are also in need of actual models I would go with Turbosquid personally, they have an awesome collection of really high quality models. You may need to open them in a 3d program and export as an FBX format, but other than that most of them are pretty complete packages.

Hope that helps!