I posted a link in here with the YSL Beauty US site, but I got a message saying that because I'm new here it'll have to pass through the moderator. I guess it hasn't made it through.
If you go to their site and go to the FAQs and type in "Opium pour homme" you get this message:
We are sorry to tell you that Opium Pour Homme Eau De Toilette Spray has been discontinued and is no longer available.
As consumers ourselves, we understand how disappointing it can be when a favorite product or shade is no longer offered. Unfortunately, demand for this product was not high enough for us to continue manufacturing it. We are sorry for the frustration this can cause.
We do not currently have a similar fragrance to suggest to you, but we invite you to visit a Yves Saint Laurent Fragrance counter where you can test our current fragrance line. For a store location close to you, please visit our Store Locator by clicking here. Enter a zip code to find the address of a store near you.
We hope that you will find a product to take the place of your old favorite soon.