Unless you don’t have a budget (who are you?), you will want to consider a sewing machine as I did to make and repair items of clothing for your career. Costs for new clothing can add up and wreak havoc on your precious income. Even discounts don’t help if you buy quality. (The axiom you get what you pay for is all too true.) Musicians in particular have to look good in black tie attire so it shouldn’t be cheap. They are viewed by the public and must blend in with others they may perform alongside if in a group or stand out as needed. If you are a soloist, it is vital to appear professional and elegant whether holding a violin, an oboe, or a clarinet.
Musicians do repeat their wardrobe of course. Few people see you twice in a week or even a month other than your colleagues. They don’t count. However, dressy clothing wears out eventually if you give a lot of concerts. It has to be dry cleaned as a rule if it is quality fabric. Machine washing and takes a huge toll. If you can whip up something new once in a while or fix a few rips and tears with the trusty sewing machine, you are well ahead of the game. Plus it is fun and enjoyable.
Now the question is: do you have time? I recommend that you keep it simple. Women wear long dresses, even intricate gowns, and have been known in the better venues to look like they are at a black-tie or inaugural ball. Sequins and rhinestones abound. Opera singers are no exception. These can be expensive, even if they are vintage. This does bring to mind the fact that great deals can be obtained in second-hand stores or online in places like eBay. Ladies don’t like to wear their apparel too many times so used items are usually in great shape. A designer dress, like a used car, drops in value when it leaves the store, but it can be like new. Take advantage of this unique opportunity.
Men who perform wear tuxes and unless they are a conductor, they are journeyman in style and cut. They don’t need to grab attention; it’s the music that counts. However, repairs are always in order to keep them looking fresh and new. You never want the public to spot anything off. Sure, you can repair by hand, but sewing machines are fast and functional and always my first choice. The bigger stars no doubt go for better brand name suits, but the same issues apply.
You say you don’t know how to operate a sewing machine? Not a problem. Your local fabric supply store no doubt will have classes. You can shop after right in the same place. If you want to make gowns, of course, you will need some skill and ability to design and execute. It can be a wonderful relaxing pastime for a musician. Again, if time permits!