Divi is a premium WP theme from Elegant Themes with many advanced features. What makes it even better is it comes with a developers license. This means you can create websites and sell them with the Divi theme installed. Note that this isn't a resale license. It's a developer license, so be sure to read the terms.
Check Divi out here and see all the features for yourself. Yes, this is an affiliate link.
Elegant Themes includes some other cool things in your membership in addition to Divi. A one year membership is $89 and a lifetime membership is $249. If you get the one year membership you can still use and install Divi as a developer but you won't get any updates, support or new stuff after your membership expires.
Buy a domain, install WP with Divi and you have an "almost instant" product you can sell. It's so easy and cheap to do you can even give these sites away as icebreakers for upsells.
Divi comes with 170+ "layout packs" which are templates for a variety of niches uses and niches already to go.
See all the layout packs here.. (Affiliate link)
Divi is really a great investment. Match a great domain name with all the powerers of Divi and one sale will easily make your money back and more.