You can find other shops that sell it by searching around on AliExpress:
I found these when searching for banana pi bpi r4 from a german IP :
https://aliexpress.com/item/1005006240132695.html
https://aliexpress.com/item/1005006371670107.html
https://aliexpress.com/item/1005006301027322.html
https://aliexpress.com/item/1005006240168403.html
Please be aware that these are potentially not endorsed by the manufacturer.