Could you possibly elucidate for me which Spanish city offers the most affordable cost of living? I'm particularly interested in knowing which locale provides the best value for money in terms of essentials like housing, groceries, and transportation. Is there a specific city that stands out as the most budget-friendly option for those seeking to relocate to Spain? Additionally, I'm also curious about any factors that might influence the cost of living in these cities, such as regional variations or seasonal price fluctuations. Thank you for your assistance in shedding light on this matter.