It is not any piece of clothing, but an essential product of dressing for me, be it any season. The most expensive thing that I have bought until now for my dressing are the sunglasses of Dolce and Gabbana.
The sunglasses were classy as hell, and I had to have them for me. Those black wayfarer style sunglasses were just too elegant to resist, especially when sunglasses are an important part of your dressing up. They cost me around 25K but they were totally worth it.