If you're a budget-conscious shopper, your best bet is this Superdry Rucksack. It's a terrific product, while not very pricey. Also look at this Kipling Backpack. It's a product you're bound to love which also doesn't cost the earth. You might also want to consider this Picard Backpack. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're not the one to skimp on clothes, then you won't be disappointed if you check out this Fendi Rucksack. It's a costly but smart option. While you're at it, also have a look at this Moschino Backpack. Yes, this item is expensive, but it does not mean it's not worth it. It is also worth taking a look at this Anya Hindmarch Backpack. You won't regret the money spent!