If you already have MarketPress, then you are benefited from the best way to setup your own store in the fastest and easiest way possible. You can be selling in no time; moreover, it fits seamlessly to any WordPress theme.
But if you want a better theme for MarketPress, do you know that you can theme it? Poke around with the basic themes or create a completely new theme out of it.
In this blog, we’ll show you how to theme MarketPress as easy as you theme your WordPress site.
Make your store unique, follow this tutorial: http://wpmu.org/the-easy-guide-to-theming-marketpress/