OpenCart is meant to be a free open-source ecommerce platform. It's very popular, but only because people in general don't realise how limited/bad it is. Once you start taking things like SEO and Usability seriously (which if you want rankings and sales, you have to), you end up having to pay hundreds for patches and extensions. When I filed some bug reports, the owner of OpenCart responded, calling me an ***, saying I was a liar etc. He all but swore at me. He then started deleting the bug reports and barred me. I now have no way to fix the issues his poor code has caused me. I'm having to pay another designer to build another site using a different platform (this time I did research, and made sure that it was community based and doesn't have some madman running around insulting people!)