Hello Haukka81,
look at ebay. Here in Europe they are rarely to get, especially the last years, but at ebay USA or Australia they are still often for sale. I got all my SFS, with the exception of my first one (bought in a computer game store in Munich), at ebay.
Sadly after my
HOTAS-Convertion-Orgy there is none left for sale, but I really believe, you still could find one at ebay. Just a little patience and you get one. Here in Germany is a ebay service called "ebay Kleinanzeigen", didn't know if the country you are from has something comparable, but this is a real gold mine for getting old
HOTAS like Suncom SFS and Talon or Thrustmaster FLCS, F22, TQS etc. relatively cheap.
Cheers Viper
P.S: Search also for "Suncom F-15", I've found most of them using this search tag.