Well, one option is to sign with some ISPs specifically geared for online sales. They start at $250 per month plus percentage of sales, but can be up and running in days. This, of course, implies that one needs to generate enough sales volume to absorb the fees.
Besides that, I would recommend looking into some "ready-made" site templates that include shopping cart and sales. Look here:
http://www.ecommercetemplates.com/ or here:
http://www.x-cart.com/
This, of course, implies that one needs Dreamweaver (expensive) or knowledge of PHP/MySQL to get the site up and running.