When I was considering switching to CS-Cart, I searched this forum for recommendations for good development teams to use, so I thought I'd pay it back by recommending the one I ultimately chose: Alt-Team.
I'm very picky in terms of design and functionality, and I have to say the guys at Alt-Team are the most patient people in the world! They ported my old store from OS Commerce into CS-Cart and designed a whole new skin for me. We encountered a lot of snags along the way, getting things to look right and work right, but they kept to their quote and got back to me daily on the status of the job. They even helped me understand how to use CS-Cart to a degree, so I can manage the store on my own. I was nervous working with a foreign company at first, but they have proved very knowledgable and meticulous!
I also needed some customizing for downloadable products, which they did. Only drawback is that they seem really busy!! So you may have to wait to get your project started, and it may take a while longer than you expect to complete. Just build in extra time to your schedule because it really is worth it to find nice people who do great work. I got a good, working, effective shop in the end–at a reasonable cost. Two thumbs up to Alt-team. http://www.alt-team.com/