Crop tops are something everyone and their mother owns in multiple colors. They're great for wearing with high-waisted shorts over the summer or skirts because you can avoid that bumpy, tucked-in fabric look and show off a slight bit of skin without being trashy. Cotton varieties are the best because they fit snugger than ones made with spandex and are generally thicker and softer, meaning more comfy and less see-through! American Apparel's Baby Rib Crop T is one of my favorites, but unfortunately it's $24 regular price. Even the one I got on sale with a promo code was still around $12. Since crop tops are basic and versatile, I think it's better to have cheaper options with more variety in colors.
Forever 21 updated their online store with a similar style for only $5.80. So far, there are three colors: Ivory, Black, and Burgundy. They're 100% cotton, so size up as they might shrink in the wash. However, they look like an awesome purchase, both for style and comfort!
(Left: American Apparel, Right: Forever 21)
Link to Forever 21 Crop Top: