I would suggest doing this trophy after you've saved up anywhere between $3,000 to $4,000 dollars. In order to obtain "Sharp Dressed Man," you have to buy out at least 3 stores. Try to shop at Aquaberry LAST, that store is the most expensive and will eat through your funds quickly. After you purchase 250 clothing items, the trophy will unlock. The best way to earn money in the game is to do all of the missions available, win races, and mow lawns in that order.
I, personally, did not buy haircuts. I stayed strictly to Tops, Bottoms, Left Arm, Right Arm, Head, and Shoes. I don't know if winning items from the Souvenirs tent in the circus counts, but it's better to spend your money at the stores versus trying to win tickets to use in the Souvenirs tent.