ISSC in Austria is part of the GSG stable of firearms manufacturers and I read the other day in one of the gun magazines that an out-of-court settlement has been reached with Glock to stop importing the M22 and redesign it to look a lot less like a copy of Glock pistols. GSG was sued by Heckler & Koch for their copies of the MP5 submachine pistol in .22LR and reached an agreement with H&K to stop the import of those and redesign it to be a lot less like a copy of the MP5.
This latest agreement between GSG/ISSC and Glock means no more importation of the M22 until it is redesigned. Hence the price drop as the U.S. importer, Austrian Sporting Arms of Ware, MA, unloads it's inventory of M22 models. The price cut is a great deal if you're looking for a Glock training pistol so if you're interested you better act now. When the importer sells out, there won't be anymore Glock-copy M22s.