Hi Dgoodin.
I use ShopSite8. It is the best I have seen yet.
You can get a free demo at http://shopsite.com.
If you like it and want it then you need to find an autorized re-seller. I use BizLand.com. I am extremely happy with them as well.
You will need to sign up under their commerce plan to get ShopSite. Expect to pay $35.95 per month. http://www.bizland.com/bizland/commerce.bml
Contact me if you have any questions. I have been using them for months and know the ropes pretty good.
I am not plugging these 2 companies for gain. I make nothing to refer you. I am just very happy with both companies product and service and want to pass it along.
Jeff