Anything close to Magento on .net?

Hi, im looking for an ecommerce solution thats free/open source and as close to magento as you can get only on .net. ive tried nopcommerce which is widely promoted as being this solution but its miles and miles off being as well rounded as magento… it cant even do simple things like seo friendly urls without having to drop an ID into them.

c’mon .netters there must be something as good!

thanks
mark