Why was trading through the Mediterranean so expensive?

Trading through the Mediterranean was expensive due to several factors, including high transportation costs, taxes, and tolls imposed by various city-states and empires along trade routes. Additionally, the need for ship maintenance and the risks of piracy and unfavorable weather conditions added to expenses. The complexity of navigating diverse political territories and the demand for luxury goods further drove up prices. Lastly, the reliance on intermediaries in the trade network often resulted in increased costs for consumers.