Matt Cutts, in his recent video explained about ecommerce product pages which becomes as no longer available when product is sold or out of stock. Matt said that it is must that you take care of usability and should render correct page to the visitor seeking the information, you should make such pages as 404, 301 redirect or use Meta tag ‘unavailable after’ as per type of website. Here is how you should do it as per type of website:
- Small Ecommerce Website: If you have small website with few products, you should use such pages to direct users to other related products or give them suggestions which product they can buy similar to that product.
- Midsized or Medium Ecommerce Website: Matt said that such websites should do 404 for such product pages, if you have website with 100+ product pages. You should take care of your visitors usability for such websites, and they will have more trust if you serve them what they are looking instead no longer available product pages, doing 404 or redirecting them is the good option
- Gigantic Ecommerce Sites: Sites like craigslist where product becomes unavailable frequently should use Meta tag ‘unavailable after’ so that search should stop indexing such pages after mentioned dates in this tag
Matt also suggested that if you think product will be available soon again, you can keep such pages for some time and when product is available, you can use the same page.
As Matt said that there is no direct relation with search engine rankings, it is more related with usability and experience of end user with your ecommerce website.