Have you guys considered a "Back in stock notification" feature? I wrote one years ago, and it works pretty slick. Basically a shopper sees a "Notify Me" button on a product page when out of stock or purchase disabled. Clicking it renders a popup so the shopper can submit an email address.

A new mailing list is created and named based on that product SKU. The shoppers email is added to the list.

This process repeats allowing for multiple shoppers to sign up to the same single mailing list depending on which SKUs are out of stock.

Every X minutes, a process runs that looks at each mailing list with the SKU name. Then it finds the product with that SKU. If the SKU is now in stock, the designated email template is sent to each list member. The mailing list is then deleted now that the members have been notified.