Themefisher is a great website where you can find themes for Bootstrap not everyone knows about. The Themes are very beautiful, detailed, animation-rich but also simply structured and focused on content.
There are a lot of free and also premium themes available, while the premium ones are sold for around 30 dollar per license. If you want to use a free bootstrap theme without purchasing the premium version of the theme you have to give attribution (simply by not removing the link in the footer of the theme)