Lol. What's with all the 10K plus quotes for stuff?!? I don't recall anyone in their 2nd years dropping 10K plus on clothes. Some 1st years did - but typically they realised no one cared about that stuff by the 2nd wardrobe update.
I reckon you can set up your initial wardrobe for around 1-2k (or less) dependent on how much you want to spend. It's about how the clothes look on you, not the brand.
Moreover, in reality, first years are the newbies at the firm. It doesn't matter how sharp your suit is, you look 21!! That means you don't have any real work or content experience behind you and so you can't really do anything! Since everyone (clients and colleagues) can see this, no one is expecting much other than for you to work hard, aim to learn lots, do the rubbish 'cut your teeth' jobs and follow the rules.
MY VIEW ON WARDROBES - LOOK PROFESSIONAL, BUT YOU'RE NOT AT GUCCI. IN FACT, THE ONLY MODELLING WE DO IS BUILDING EXCEL MODELS!
Watch - analogues only (digital is just very studenty). If you don't want to shell out for a decent one (I'm thinking 0.7K - 1K, not 5k!) then just don't bother with it.
Suits - 3 is fine. Paul Smith at 700 quid is good, but then so is every other brand out there pretty much. All that matters is that it doesn't look cheap and that it sits well on you. I personally found a great way to waste money was to buy mid-market (e.g. Calvin Klein). They tend to be of the worst materials. Either splash out on a high-end brand or buy something cheap that looks good (believe it or not, even Debenhams gets the job done). Also, you don't need to buy all 3 at once. 2 initially is fine (just make sure they're reasonably non-descript) then buy the 3rd later when you find a good deal.
Shirts - no one cares, you can barely see the shirt under the suit anyway. TM Lewin / Hawes and Curtis get the job done, but so does M&S. Say 7 shirts at 30-50 quid each. Once again - it's about the cut, not the brand. The only key point is to make sure your shirts are primarily whites and blues (possibly with a pink and avoid yellows unless its just the shirt lines that are yellow)
Ties - nice ties are important. You can buy 'nice' ones for between 30-50 quid. The only reason they're important is that the material quality is most evident on ties - and the label is more likely to show. Dependent on your role you may never have need for them though. So maybe you only need 2-3 in some jobs.
Shoes - 1 pair to start you off is fine. Think 100-150quid. Check the soles of the shoes have a good grip, else you'll slip on the ibank floor and look like a pr1ck. Some also have the clacking noise of high heels - that's not good
The key thing is to remember who you are - you are a 1st year and you can't do anything yet. Sorry if this bursts the high-end glamour illusion of banking that first years sometimes mistakenly perceive. Banking is a knowledge industry - and all your academic knowledge is broadly useless in the job. If you want to nail the job, you need to work hard and make sure your output is top-notch. Maintain a PROFESSIONAL image (e.g. no black shirts) since that's a required and expected minimum, but don't start dropping all your hard earned cash trying to look like the dog's b0llocks. No one cares and rucking up in your 5K get-up just tends to be perceived by your seniors as sweetly naive!