Looking over his Ebay listings he does have EVO parts for sale. I did not see the part you need but if I was you I would email him and see if he might have a old broken gimble that he could strip out the part for you. Worth a try I would say.
Autel will not just sell you any parts unless you send it in for repair. Might be another option. Sometimes they cover shipping both ways even if its not under warranty.