Depends on the needs your customer have and want for the project. Those three factors you always need to have into consideration.
Durability does play a minor factor in cost but the most expensive products are the natural products. The reason is because natural is more beautiful for example if some was selecting a tile i would recommend porcelain because its the most durable and les costly but if i have a client who likes beauty i would recommend he buys a marble or granite or even a travertine tile because they look much better than porcelain.