Paid or Premium WordPress themes can have there benefits. Better coding, support, and features plus for a very low cost you can get access to an enture suite of high quality professional themes. But a lot depends on your site and what your intentions are.
In this particular WordPress theme training, not only do I provide you with an extensive resource list of great sites (below) for buying awesome themes, but I also go over the process of installing themes manually. Which is usually required if you are not installing them from the WordPress repository.
My Favorite WordPress Theme Resources:
Please note that some of these sites may also have FREE themes for you to download! 🙂