At Kickstart Commerce we like to focus on functionality and sales with our e-commerce websites, and many of the sites we are involved with were built on that model and trade very successfully.
This isn't to say we can't do "style" as well. We just like to make sure the functionality and ease-of-use of our builds are rock solid before turning our attention to design.
One example is the site www.lucagobbi.com which we re-themed. When you are looking to change the design of your site, there are a couple of options. One is to pick one of the off-the-shelf themes that are in the BigCommerce marketplace and this can be a cost-effective method to get you most of the way to how you want your site to look.
The other option is to take a theme like cornerstone, and customise it to what you want. And you can of course build a theme completely from the ground up, but that is a more time-consuming and costly exercise.
In our experience, getting the site working on one of the standard themes is a route we like to take. Re-theming is then the nice part either at the end of the build, or some time into the life of the website.
If you are interested in a BigCommerce build, get in touch. We have some great starter packages and we also have a lot of knowledge about running e-Commerce sites overall.