The main difference I see from expensive clothes and just normal prices clothes is the brand. You can get the same quality of clothing without an 'expensive' brand for a lot less money. You just have to know what materials and stitching you are after. At the end of the day, seeing someone with a tiny logo on their t-shirt doesn't make me think 'Oh, that person must be rich!', no, anyone can afford a £100 t-shirt if they wanted it. My friends were saying I should buy a load of expensive branded clothes; whilst I could, I don't see the point. They said "Because people will know your loaded", that seems like such a stupid reason!
I buy quality clothes, but not well known brands just because I'm getting the same quality of clothing for 10x the price for a little logo or what not. Although, I would warrant spending a lot on a suit or any clothing made to fit that needs to be tailored. You can defiantly the difference of a £300 suit to a £1000 suit; they can last for 5-10 years if you take care of them!