Which of the following is NOT a factor affecting material costs?

Market trends do not directly influence the inherent costs of materials in the same manner as the other choices. While market trends may affect the demand for certain types of materials, leading to fluctuations in price, they do not alter the fundamental characteristics of the materials themselves.

On the other hand, the ease of transportation can significantly impact material costs due to the logistics involved in moving materials from suppliers to manufacturers. High transportation costs can inflate the overall price of the materials. Aesthetic values are important in determining the desirability and perceived value of certain materials, which can influence their market prices. Durability affects material costs as more durable materials often require advanced processing and higher-quality components which can lead to increased expenses.

Thus, choosing this option stems from the understanding that market trends relate more to market dynamics rather than the direct cost attributes of the materials themselves.