Drupal Commerce - Out of Stock, customer clicks to notify store owner to order more When a product is out of stock, the store owner wants customers to have the ability to pre-order, without paying.
Similar to stock notify, but the store owner will manually email back customers once the stock arrives.
Something like'This product is out of stock, notify us, and we will order it in for you within 1 week.'

So it needs to collect: customer email and product SKU.
As many customers will be non-registered users, what would be the best way of capturing this data, and emailing it to the store owner?

I was thinking flags/rules module, or do you think a custom module would be simpler?

Thanks in advance.
There are two similar kind of sandbox module for this particular functionality. 

One was started by me - Commerce Stock Notify

Another by itamar - Commerce Stocklist. 

Both can be starting point for further development. As I left doing anything else for this as he started it before me, but my module do what you want except mail template which I was supposed to do later.

But now I think, I will spend some time on it &amp; try to release stable soon :)