I rewrote a PHP plugin for vitaminandme.com that plugins in answers to a questionaire and recommends the best vitamin combo for that person. It is especially helpful for pregnant and nursing mothers.
We utilized Gravity Forms for the survey and WooCommerce Subscriptions and WooCommerce Product Bundles for the shop. We configured the WooCommerce extensions so a client could subribe easily to a recurring vitamin bundle.
The website was rebuilt in Divi during this process.