There are several reputable online platforms where you can purchase bronzer sticks. Here are a few:

1. Sephora: Sephora is a leading beauty retailer offering the best cosmetics, skin care, makeup, fragrance & perfume, hair, beauty products, and makeup tips.

2. Ulta Beauty: Ulta is the largest beauty retailer in the U.S. and the premier beauty destination for cosmetics, fragrance, skin, hair care products, and salon services.

3. Amazon: Amazon is a vast online marketplace where you can find a wide range of bronzer sticks from various brands, both high-end and affordable.

4. Nordstrom: Nordstrom offers a wide selection of beauty products, including bronzer sticks from luxury brands.

5. Beauty Bay: Beauty Bay is a global online retailer that offers over 10,000 products from the very best UK and International brands.

6. Cult Beauty: Cult Beauty is a UK-based online beauty store that curates the best in beauty from around the world.

7. Dermstore: Dermstore offers professional-strength formulas from top skin care brands, otherwise only available from a dermatologist.

Remember to check the ingredients of the bronzer sticks to ensure they align with your skin type and preferences. It's also important to read reviews and product descriptions before making a purchase.