If you're a thrifty spender, your best bet is this adidas by Stella McCartney Rucksack. It's a wonderful item, while not very expensive. Another strong contender for your wardrobe is this Rucksack. While the price of this product is not very high, it will definitely attract a lot of attention. You may also want to look at this Kenzo Backpack. This item is not expensive either, but it will make a difference in your wardrobe.