Account permissions will allow you to give people access to the product admin only:
I would also take a look at the Transparent Kitty app, which is helpful managing sales and commissions for third party sellers:
Good luck with your shop!
If you change the Admin access as described (product admin only functionality), can that user view/change/etc all other products already listed on the website? If so, that will not work for me.
I am also interested in an app that allows 3rd parties to list and sell their goods on my Shopify website (I don't have one yet, so I'm asking questions first). I want them to have the ability to register, then sell products wherin I take a percentage of the sale. Obviously, they should only have access within their listings and nobody elses.
If nothing is available as such, can a 3rd party developer do this?
The solution I described would allow the user to edit all products, so it may not work for you.
There are apps, like the one I mentioned (Transparent Kitty), that divides profits and sales. Currently, there isn't an app for a full-on "ebay" like marketplace experience for your third parties.
A third party developer may be able to do this, building a complex app via the product API. Restricting permissions by user would be challenging.
You can reach out to a Shopify expert at experts.shopify.com