Can anyone sell on The Sandbox marketplace?

Yes, you can sell these ASSETs on The Sandbox’s Marketplace if you wish .

Who can upload NFTs onto the marketplace to sell? Initially only those who have been accepted into the Creator Fund will be able to upload pre-approved and commissioned ASSETs onto the marketplace (in other words, they cannot just upload whatever they want).

The price of an NFT sold on The Sandbox Marketplace is entirely up to the artists or seller of that NFT . The seller would need to ensure the price is fair and competitive based on scarcity, uniqueness and so on.