You can do what you're asking relatively easily, without loss.
Here's the best way for you…
Just create a new installation of WordPress into a subfolder you name "Store" or something simliar. In that folder you will setup your install of Market Theme on that WP install.
Then, on your homepage navigation, you'll simply need to add a new link that goes to the sub-folder installation.
A lot of members do it this way.
Here's a support post on that topic:
http://www.markettheme.com/for…..arate-blog