If you're in a thrifty mode, your best bet is this FjallRaven Backpack. It's a great product, while not very pricey. In this price range, you can also take a look at this Parfois Backpack. It's also a popular item and won't break the bank. You may also want to look at this Vans Backpack. This item is not expensive either, but it will make a difference in your wardrobe.
If you're looking for something in between pricewise, look no further than this Furla Rucksack. This item won't break the bank, but absolutely essential in your wardrobe. You might also want to check out this Philipp Plein Rucksack. It's an attractive option both price and quality-wise. And do check out this See by Chloe Backpack! It's a very popular item and good value for money.
If you want to splurge on a luxury piece, then you absolutely must check out this Versace Backpack. This product seems expensive, but it's top quality. While you're at it, also have a look at this Burberry Backpack. Yes, this item is expensive, but it does not mean it's not worth it. And one more item you might be interested in is this Valentino Garavani Rucksack. 'Cause you deserve nothing but all the finer things!