as somebody who dresses part time like this, my number one suggestion is to not look for the big brands resellers love to show off!! you do not need affliction, harley davidson, DC, fox, etc to look the part at all!! i wear hurley, oneil, even urban planet/walmart clothes and still 100% look the core! thrifting will be your best bet finding these clothes, but ebay, depop, threadup can work for you too, just do not search specifically for "older brother core" clothing!! anything you search for with "core" in the name will bring you overpriced clothing, but if you're more broad with your search, you can find those needles in the huge haystack that is 2nd hand clothing!! do not expect to find exactly what you're looking for, but compromise (especially if the price is cheap!!). if you have anymore questions, please reply!! i am going to be-online tonite and tomorrow!! :D