I used to do online sales for people. I charged a cost + percentage and had to have the item in hand. I don't do it anymore, it just isn't worth it. If I did I'd have to charge you for storing your surplus stock, and for my time as well as cost + percentage.
I suggest you hire someone to handle this on an hourly basis. If your stuff isn't worth selling that way consider selling it as a lot to someone who is in your business.
