Swap Platform

Hello I would like to create an online platform where users can log in and upload products (that me as an administrator need to approve). Every product needs to have a name, description and picture upload and the user can decide the value of the item uploaded.
Users need to be able to contact each other on the platform and exchange messages.
When products are swapped (goal of the platform) the product needs to become unavailable.
Maybe users need to pay a fee to subscribe to the platform but still to decide.
Thanks