There are a terrific amount of retail outlets on the high street in chain stores that carry a range of boys' clothing that reflects the trends of the moment. Some of the bigger stores that are predominantly used for grocery shopping have sections that retail boys' clothing along with baby wear, girls, women and men's too. They are nationwide and often have designers who provide exclusive collections for those outlets at competitive prices.
Boys' clothing ought to refer to the 7-16 age group as their purchase is normally made by adults from their home or the ability to make purchases themselves is provided by parents through pocket money, allowances, presents and perhaps for the older boys a small remuneration from a part-time job. Shopping for clothes with Mum is almost taboo, Dad very often is reluctant to trail a truculent teenager or young boy who'd prefer to be playing in the park or with his console around the shops and trusting a boy to make a purchase that is 'sensible' and value for money is fraught with problems. Perhaps the only 'cool' store is far away and requires a trip on the train to get there, a return could be difficult especially if the boy doesn't want to appear a sop or didn't have the wit to retain the receipt. Without someone to assist in the purchase of what looks well - how many boys avail of changing rooms...very few - money can be wasted. So, more often than not boys' clothing is purchased randomly without consultation or even the boy present to give a nod or a wink in approval of the choice.
We need to educate boys how to shop efficiently and effectively and the first step is to listen to what there preferences are and measure them to find out what size they take. Once in possession of their vital statistics it is possible to determine which 'fit' of jeans or T-shirt best suits or is desired. However, different stores and different designers show a certain disparity in their sizing despite industry standards and of course any boy between 7-16 is going to have growth spurts that don't necessarily fit in with your planned budget. Shoes have to fit otherwise they can deform the feet. It might be possible to get away with slightly short jeans or a T-shirt that's a bit snug for a while until you can but replacements but footwear always has to take immediate priority.