I was part of Auctomatic, and I still think inventory management is a space to be disrupted. I think that we were free from day one was a reason that people were reluctant to start paying.
The one trouble with eBay inventory management, or any space where there are existing competitors, is every user has their own pet feature they absolutely can't live without. It becomes a battle to implement them all and keep a clean interface.
Also make sure you can import everything from every competitor. It lets people try your software very easily and gives you all of their data. So even if they don't become a hardcore user you can see what one looks like.
The one trouble with eBay inventory management, or any space where there are existing competitors, is every user has their own pet feature they absolutely can't live without. It becomes a battle to implement them all and keep a clean interface.
Also make sure you can import everything from every competitor. It lets people try your software very easily and gives you all of their data. So even if they don't become a hardcore user you can see what one looks like.