I made the same discovery during our recent road trip (yes, David, I'm working on the report!). I, too, was wondering if 95 has been banned altogether. Not that I can find the stuff in the BKK area either, mind you...!
Then again, I find my engine runs nicely on 91. Does anyone know of detrimental effects on engine components?
The only place I've been able to find benzine 95 is at the Shell station on the left just after you pass the turn to 1095 in Mae Taeng. Otherwise I use gasahol 95 in my 3-year-old Phantom with no negative effects but it seems to run and even sound stronger with a tank full of the 100% benzine.
Coming in the 118 from Doi Saket cross over the superhighway traffic lights and a couple of hundred metres down on the lefthand side is a Shell station selling it. Price 27.14 baht per litre (6 hrs ago).