Temu would be a reproduction, right? I don't know, never really used it. You can get the real thing for around $150-200 depending on condition and grade. A small amount to spend for all the work your wife put in to qualify!
Haven't checked Evay but I'm talking direct militaria dealers. The Gettysburg Museum of Military History is always a good one. Not sure if they're in stock now but they come around. That site has had some interesting (and expensive) stuff for sale. You'd think it would be all civil war stuff but they have a large selection of NSDAP stuff.
Egay has no stock whatsoever (probably because of the swastika)
and the place you mentioned already sold their stock
https://www.gettysburgmuseumofhistory.com/gettysburg-battle/world-war-ii-militaria/original-cased-wwii-era-german-mothers-cross-ehrenkreuz-der-deutschen-mutter-in-gold-certified-92/
Yeah it comes and goes. They have them occasionally. Just have to watch out. There are other sites but don't have the link handy. Best not to look on major websites.
Egay has no stock whatsoever (probably because of the swastika)
and the place you mentioned already sold their stock
https://www.gettysburgmuseumofhistory.com/gettysburg-battle/world-war-ii-militaria/original-cased-wwii-era-german-mothers-cross-ehrenkreuz-der-deutschen-mutter-in-gold-certified-92/