This TruSkin Naturals Vitamin C Serum ($20) is a bestseller. According to the brand, the serum is "proven to reduce the appearance of wrinkles and fine lines while helping boost collagen, fade sun and age spots, improve skin firming, brightening, and tone for a smoother, fresher, more revitalized youthful complexion." I know it sounds too good to be true, but it actually works.