The cost of selling on Amazon for a month varies depending on different services and needs, and generally includes monthly service fees, sales fees, storage fees, delivery fees, and advertising fees. The price of the monthly service fee varies by sales plan and country, while the sales fee is based on the price and category of the product. Storage costs are usually determined by the number and size of items stored, while delivery costs are calculated based on cost, distance, and packaging. Advertising costs depend on the method and budget of advertising. In general, the cost of selling on Amazon for a month varies depending on the service and needs, and requires specific inquiries or calculations based on the relevant service rate table.