In my experience, a marketplace always requires large investments in marketing (((the problem of such a business is a chicken-and-egg issue. Clients will not come to the site until there is an insufficient selection of goods and sellers, sellers will not come to the site until there are not enough potential buyers. It’s more convenient to start by attracting unique sellers and products, but for this I would use direct sales, offer special conditions for the first sellers, and then launch advertising on products and product categories in order to gradually gain a base of potential buyers.