Hi,
Builder is a theme framework that gives you all the flexibility to make the site look like you want. You will have to add your own styling (through CSS) and you will need a shopping cart/e-commerce plugin as well. Is it capable? That all depends on your coding skills, in particular php, html and css. I suggest you watch the tutorials on Builder (http://ithemes.com/forum/index.php?/forum/65-builder-tutorials/) to see what you get, and watch the webinar as well (http://ithemes.com/forum/index.php?/topic/464-builder-theme-15-hour-webinar/).
Ronald
