I called Bigcommerce and asked them for advice when I was starting my store. The two companies they recommended were Mad Wire Media and New Dynamx. I spoke to both companies but found New Dynamx to be more professional and worked quicker.
I worked with the guys at New Dynamx and they were great. My site was designed perfectly within a few weeks and they also helped me with some SEO. So far, so good. Here is a link to their webiste:
www.newdynamx.com
