Such stuff (lots of it!) is always available at silent auctions at such events as the Hardwood Club Dinner, the Boeheims' Basket Ball, and many other events sponsored by the SU Athletics Department. I suspect Brandon Steiner also has a lot of it for sale. https://www.steinersports.com
Any chance SU bought any of it to add to their collections?
Not speaking on any sort of knowledge about this, but I would have to assume that the majority, if not all of what is in their collections is stuff that they own or that was donated to them. I doubt they are in the business of purchasing sports memorabilia at auctions.