Denim is one of the most comfortable staples in a woman's wardrobe. A good pair of jeans will get you through any day in style. Besides, they always got your back when you have exactly 60 seconds to decide what you're going to wear in the morning.
If you're a thrifty spender, your best bet is these True Religion Jeans. It's a popular product, while not very pricey. Another strong contender for your wardrobe is these Rag & Bone Jeans. While the price of this item is not very high, it will certainly attract a lot of attention. You might also want to consider these Current/Elliott Jeans. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.