Vitamin C is a potent antioxidant known for brightening dark spots, protecting skin from environmental damage and promoting collagen. In fact, it’s so beloved for these benefits that the ingredient even has its own nationally recognized day. Vitamin C Day falls on April 4 each year, and to celebrate, we’re rounding up where to stock up on your favorite formulas for less. Ahead, shop 15 vitamin C serums we found on sale.

Amazon

To no one’s surprise, Amazon has several dermatologist-recommended and cult-classic vitamin C serums on sale, starting at just $11. Highlights include viral K-beauty formulas from medicube and Dr. Althea, Hailey Bieber’s go-to brightener from BeautyStat, editor favorites from Sunday Riley and Paula’s Choice and affordable staples from The Ordinary and Good Molecules.

Nordstrom

At Nordstrom, we found three vitamin C picks for every budget. For under $25, there’s Timeless Skin Care’s vitamin C serum, packed with ferulic acid (one of our favorite skin-care duos). A little higher on the budget, MISSHA’s Vitamin C set is a standout value, featuring two sizes of the Vita C Plus Spot Correcting & Firming Ampoule, two sizes of the Vita C Plus Eraser Toning Cream and cotton facial pads. Finally, for under $75, FRÉ’s vitamin C formula uses 10 percent Ascorbyl Tetraisopalmitate, which the brand says “lasts up to 80x longer than traditional L-ascorbic acid.”

Ulta Beauty

There are three standout vitamin C deals at Ulta Beauty as well. Cult favorite Seoul Ceuticals has a near-perfect five-star rating, thanks to a formula with vitamin C, ferulic acid and hyaluronic acid. Similarly popular, TruSkin’s vitamin C serum includes aloe vera and vitamin E to help stave off dryness and irritation. Indie Lee’s clean approach features superfruit camu camu, along with squalane, CoQ10 and green tea.

Honorable Mention

At Dermstore, several skin-care sets are currently marked down, including a duo featuring the holy-grail vitamin C serum, SkinCeuticals C E Ferulic, and the equally beloved Triple Lipid Restore 2:4:2 moisturizer. SkinCeuticals rarely goes on sale, so getting both for under $300 is almost unheard of. Grab this one while you can.

SkinCeuticals Anti-Aging Radiance Kit with C E Ferulic Vitamin C (was $340, $299)