One of the biggest issues facing e-commerce sites & classified sites is something we call “product churn”. Every time a product or advert is deleted from the database it leaves a blank page causing problems for users and search engines.
Most platforms handle this issue pretty badly, the “solutions” range from blank pages, 404 pages, product not found pages that return 200 status OK headers and many more. My solution has been the same for years and it works very well to keep search traffic and make your users happy.
The first thing you need to make sure is that your expired product stays in the database, deleting products means deleting pages and that won’t help your Google traffic. Ideally you need to keep your listings live and in the Google index.
The key is to keep your page title, subject and content the same and simply add a note saying “This product is no longer available, below are some similar ones”. Make sure you don’t put the product name next to the words “no longer available” otherwise this phrase might show up in the search snippet and lower your CTR.
Once you have the page created you can add a section for related products by querying your database for the name of the expired item. Make sure you have some solution in the event you have no other matching items such as links to the top selling products in a category or even deals pulled from eBay.
Anther good tweak is to have a search box pre-populated with whatever query the user had entered into the search engine they used to find your site. That way they can easily search your site for the exact product they wanted in the first place.