In 2009, as huge majorityy of development companies we use eCommerce CMSs (ZenCart mostly but not limited to it).
The main challenges were to integrate their business model into the logic of these free Carts software / website and we did it all the time.
Real problems started when CMSs receive upgrades and all free and highly customised (by us) modules/add-ons/plugins used received or not upgrades from their developers.
All over, after a few years we hardly cope with so many very custom implementation for so many clients. The worst was that to be able to properly maintain all these ecommerce website we start spending more time and obvious we had to ask more and more money from our customers.
That was the moment when we start building this beautiful piece of software, OLALA Shopping Cart.
The OLALAL Shopping Cart allows us to provide software and world class level of services at a fraction of price.