I'm fairly familiar with OS Commerce and a few other similar carts. However I'm looking for the easiest most cost effective way to get a site online and selling.

A few details:
We will be selling physical goods.
We will be operating multiple sites in multiple niches.
Search engine friendly URLs are important to me.
Ease of uploading product is important.
Multiple design templates are important.
We will be operating both wholesale and retail site so the ability to have the customer purchase via cc, check and/or purchase order (Net Terms) is very important.

Please give your thoughts and any other suggestions you may have.

Thank in advance for you help.

i'm also researching the same. Here are a few options that could seem to work.


software
shopsite
viArt shop

service
1shopping cart

you might also want to check out these great resources on the web:
-www.tamingthebeast.net/articles2/shoppng-carts.htm
-http://shopping-cart-review.toptenreviews.com/index.html

I have used os commerce and a few of the other free carts out there.. Personally I prefer and use zen-cart to manage my stores. For me its a perfect solution.