W3 Custom Product Options

So far the best product options app I've used/tried. And I've tried A LOT! They did a great job at making sure to add all the little awesome details you need to make your online store work seamlessly.
I would 100% recommend this (and will) to anyone.
I also LOVE the fact that I can call them on the phone if need be for help. That is so rare now a days. It's SUPER helpful!