Maybe try local pawn shops or thrift stores. Im lucky I got my Extreme 3D pro back in April, They were sold out from December 2019 to March? April? 2020 on Amazon, and I checked now and LOL paying 100% added sticker price for used or "new" 3D extremes (70 to 100 dollars!) When the two I bought (one in 2018, the other in April 2020 mentioned above) were 35 dollars each
Maybe try newegg.com as another website.