Same question here. It seems that with Phonak PFE Audeo division closing down, the few suppliers of Phonak silicon tips outside US (so excluding Audeoworld) are now running out of stock. Actually I had my silicon M on order for 2 weeks, and then the order was cancelled due to missing stock. There are still some L and S available, but Ms are really disappearing. And I'm talking about Switzerland, where Phonak is actually coming from, so I'm afraid it'd be even worst in other countries.
Checking some threads on Head-Fi, I saw that some users mentioned that the q-Jay and Shure PA910 tips are working fine with Audeo earphones, but all the comments were for triple flanges tips, not "single flange" ones.
I'm actually looking for standard tips as I like the original shallow insertion of the original Audeo tips, but I'm afraid I'll need to migrate to the triple flanges, which I heard are changing a bit the sound of these earphones