You won't find them. They have been discontinued for close to two years, and if you do find them on Ebay they are going to have a huge price premium associated with them.
Unless you can find them in bulk, there are other blades that are more cost-effective and stocks of the Bleue Extras are very limited now.
A sample pack of Gillette blades or medical prep Personnas would be a good starting point for alternatives. The Super Thin Platinums are also one of the best current production blades and are extremely good value.