Thanks for that info, makes more sense now, my bad for missing it originally.
Since it is UID only auth you can really use anything that is 7B UID changeable. The one thing I would question is if it checks ATQA and SAK and UID which would be a limiting factor.
This is most likely the more reliable retailer for 7B Gen1a MFC. Of course, you’ll be able to find some available elsewhere but it may be more trial and error with less descriptive product details. From my experience, you are more likely to find a 7B Gen1a with 4k memory rather than 1k (not that it matters in your use case).