It is both unaffordable and unreasonable to only wear designer clothes to work in finance. You need to look both sharp and presentable, yet comfortable and simple.
Repeated laundry / dry cleaning is going to make your clothing old and frayed.
Your best option is to mix and match with a lot of high street pieces.
Every year - buy a new set of basics from Zara, Mango, Reiss and J.Crew - White shirts, T shorts, Tank Tops, Simple blouses etc.
Invest in designer jackets from Armani, Alexander McQueen, Balmain, etc. that you can wear year after year.
Most important is work shoes - a classic black, nude and white are my go to for work. Personally I love Christian Louboutin but any clean and simple stiletto will complete your outfit.