If you are looking to buy a unique 500-word article online, there are several platforms where you can commission or purchase content. Here are some popular websites to consider:

1. Upwork: A freelancing platform where you can hire writers to create unique content for you. You can find writers specializing in various topics and set your requirements for a 500-word article.

2. Fiverr: Another freelancing platform where writers offer their services for custom articles. You can search for a writer that matches your desired topic and budget.

3. Textbroker: A content marketplace where you can order custom-written articles. You can choose the quality level and specify your word count.

4. WriterAccess: A service that connects businesses with professional writers. You can request content based on your needs and specify the length and topic.

5. Constant Content: A platform where you can browse articles for sale or request custom-written content. Writers here produce high-quality articles tailored to your specifications.

6. iWriter: A content writing service that offers custom articles at various quality levels. You can order a 500-word article and provide detailed instructions.

7. ProBlogger Job Board: A job board for hiring bloggers and content writers. You can post a job offering to have a 500-word article written, and writers will apply.

Before purchasing, ensure the content will be unique, and confirm the writer’s experience or reviews. Many platforms provide sample work or allow you to review previous articles before making a purchase.buy online, e commerce products, online shoping,online shopping sites, online shops, shop website,shopping stores