The IFF Transponder is usually on eBay I have see them list in and out side of the U.S. this one was a steal you can not purchase switch this cheep.
https://www.ebay.com/itm/204114462732?hash=item2f862b880c%3Ag%3AagAAAOSwlgRjQc~T&amdata=enc%3AAQAHAAAAoNVOpxwgbmy0QKDZleAClXukEvVtD1v0dpVphCgjijfc6ASCSvgWiGeyPM%2FxGyw0Hx%2BFaRIL3ju4xCveVrRFBBdfyWoNxHpM6cl5GgPusmSAe%2FbN%2BjLaruy2npzoC8VwSpM%2BrzgRWBKuEzICvge5hHQZaak%2BY3A2Rs3VibMa%2BBSlfoiGhnj3Nc1tM3FfeMboZxV3JGNl%2FgAEtMDPlPS8GDA%3D|tkp%3ABk9SR-CtobWuYQ&nma=true&si=MY9ePV1ptMSecUme9hJ21B9HWbo%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557.