Right now, a big benefit to the version 3 theme is that people can offer products, but still have the ability to operate an ongoing blog.

In the future, we plant to take the shopping cart technology base of version 3 and create a bunch of different theme layouts.  Some will be blog post content weighted, and others will minimize the blog posting contect and be more storefront focued.

For what you're looking to do, you might just want to create a single homepage post containing your sales ad.  You can also create a unique page, and modify the settings to make that page return as your homepage.