This is kind of a stretch, but are you into the fashion scene in your country/city? If you know people that own clothing stores in London, say stores that cater to the hip-hop or possibly hipster crowd, you can buy clothes for cheap(er) in NYC with USD, then take those clothes maybe denim, t-shirts, hoodies, hats, etc., and sell them for British pounds upon arrival back in London. It might take a bit of leg work and risk a little money, you might have to try to hustle some to your friends/family or even through concerts/events, maybe try to hit some stores before and pitch them the idea.
From what I understand British pounds are worth much more than USD, last I heard the exchange rate was 1 pound = 2 USD. You invest $500 British pounds, which gets you $1000 USD, you take that money and buy up a bunch of clothes, you get the hook up from the young cats coming up with the screen print business, or the connects on the raw denim jeans. You get the t-shirts for $10 USD a pop which is only $5 British pounds (your money), you then sell those same t-shirts for $15 British pounds wholesale to the clothing stores (equivalent of $30 USD). So if we're thinking in things of USD you make a profit of $20 per t-shirt, if you get a hundred t-shirts for a $1000USD, and you make $20 dollar profit per shirt X 100, you make a net profit of $2,000....
From what I understand British pounds are worth much more than USD, last I heard the exchange rate was 1 pound = 2 USD. You invest $500 British pounds, which gets you $1000 USD, you take that money and buy up a bunch of clothes, you get the hook up from the young cats coming up with the screen print business, or the connects on the raw denim jeans. You get the t-shirts for $10 USD a pop which is only $5 British pounds (your money), you then sell those same t-shirts for $15 British pounds wholesale to the clothing stores (equivalent of $30 USD). So if we're thinking in things of USD you make a profit of $20 per t-shirt, if you get a hundred t-shirts for a $1000USD, and you make $20 dollar profit per shirt X 100, you make a net profit of $2,000....