Discount Ninja Promo Engine

All I can say is GREAT customer support. The app is very robust, so there are many different ways that it can be configured. It's a bit of a learning curve, but once you get it...it's NICE!!! But we were able to things moving within a couple of days after the support team did everything to make sure the app was configured correctly. They even recommended a 3rd party filter app which is compatible with the dynamic pricing.