i dont think you can buy them by themselves... (could happen in the future as they become more common and people scrap them for parts..?)
luckily, you can buy a damaged magic keyboard, take its keycaps you need (make sure it has the ones you need!) and fix yours with them :)
black keycaps: https://www.ebay.com/itm/225589036088?epid=4037926971&hash=item3486278438:g:yT4AAOSwvu1kbWAM&amdata=enc%3AAQAIAAAA8FO8XME2xI%2FkgVGpqyA4P1g1K9OHz7BJ%2Bf7Tg%2BgNOc8euBx6bTHwdY33Yk3roH8dzrCDQ0TB1qq%2FrhqNiHllFkMbVoI2ryUj0fjBJgAoVGI9RgKZGH4HqloMzygH%2FJsKclgHDpxCi6lUs8JSl7m4hezo%2BalQPbZV1o%2BRNRqHfAMEHHykrXxGk6I%2BYPPw0TkGmJOMn8DK%2F34P%2FDRGbKduXZZBtGZoHHy5er2VEyaXxRxv5tHDPCzl52KwmBhorG9p0qWATtxMhf%2FXM4z6VzXFYyUfqtAJuR4g7MB8baSpCtPzTgTxWMtAmzrgufM%2BnD3LyQ%3D%3D%7Ctkp%3ABk9SR9rijeSRYg
or white keycaps: https://www.ebay.com/itm/154978207460?epid=16045954819&hash=item24156bc6e4:g:oYMAAOSw~i1h7dPl&amdata=enc%3AAQAIAAABADv0vOqjwECwlZ7UXmden5lRJS9LH7mLS4IbXvPyPCTfK7HND3jG3mtLNKumA6ixNQLKtOYFrE1RMgq%2FWM0OSyFBXqojop6bSp1cUym7sDtK7Df8E2mH00VtpJf2%2FTpffxfZ%2FQFVjRmv42Q2tUmCaL4zl5g%2B5xJVAOWGcCPmIq9QtfawoX%2BFFwDKzboFeZj7VWP%2BqIpBGERSjNzP%2FUDhj0HtDAWFN7htpOCqCIMFbFUEjqfBbI0f2w8xC3bEZwGI3JCO4T1RAJoh82pk%2B5iMEKcwkmabSEGMp7CR2GcDhsO9q5DWv7gCvnsfagMsF2zDv4jh%2Bdg03UQZ%2BtAGsinQfuc%3D%7Ctkp%3ABk9SR86LmeSRYg
luckily, you can buy a damaged magic keyboard, take its keycaps you need (make sure it has the ones you need!) and fix yours with them :) https://www.ebay.com/itm/225589036088?epid=4037926971&hash=item3486278438:g:yT4AAOSwvu1kbWAM&amdata=enc%3AAQAIAAAA8FO8XME2xI%2FkgVGpqyA4P1g1K9OHz7BJ%2Bf7Tg%2BgNOc8euBx6bTHwdY33Yk3roH8dzrCDQ0TB1qq%2FrhqNiHllFkMbVoI2ryUj0fjBJgAoVGI9RgKZGH4HqloMzygH%2FJsKclgHDpxCi6lUs8JSl7m4hezo%2BalQPbZV1o%2BRNRqHfAMEHHykrXxGk6I%2BYPPw0TkGmJOMn8DK%2F34P%2FDRGbKduXZZBtGZoHHy5er2VEyaXxRxv5tHDPCzl52KwmBhorG9p0qWATtxMhf%2FXM4z6VzXFYyUfqtAJuR4g7MB8baSpCtPzTgTxWMtAmzrgufM%2BnD3LyQ%3D%3D%7Ctkp%3ABk9SR9rijeSRYg
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luckily, you can buy a damaged magic keyboard, take its keycaps you need (make sure it has the ones you need!) and fix yours with them :)
+
+
black keycaps: https://www.ebay.com/itm/225589036088?epid=4037926971&hash=item3486278438:g:yT4AAOSwvu1kbWAM&amdata=enc%3AAQAIAAAA8FO8XME2xI%2FkgVGpqyA4P1g1K9OHz7BJ%2Bf7Tg%2BgNOc8euBx6bTHwdY33Yk3roH8dzrCDQ0TB1qq%2FrhqNiHllFkMbVoI2ryUj0fjBJgAoVGI9RgKZGH4HqloMzygH%2FJsKclgHDpxCi6lUs8JSl7m4hezo%2BalQPbZV1o%2BRNRqHfAMEHHykrXxGk6I%2BYPPw0TkGmJOMn8DK%2F34P%2FDRGbKduXZZBtGZoHHy5er2VEyaXxRxv5tHDPCzl52KwmBhorG9p0qWATtxMhf%2FXM4z6VzXFYyUfqtAJuR4g7MB8baSpCtPzTgTxWMtAmzrgufM%2BnD3LyQ%3D%3D%7Ctkp%3ABk9SR9rijeSRYg
or white keycaps: https://www.ebay.com/itm/154978207460?epid=16045954819&hash=item24156bc6e4:g:oYMAAOSw~i1h7dPl&amdata=enc%3AAQAIAAABADv0vOqjwECwlZ7UXmden5lRJS9LH7mLS4IbXvPyPCTfK7HND3jG3mtLNKumA6ixNQLKtOYFrE1RMgq%2FWM0OSyFBXqojop6bSp1cUym7sDtK7Df8E2mH00VtpJf2%2FTpffxfZ%2FQFVjRmv42Q2tUmCaL4zl5g%2B5xJVAOWGcCPmIq9QtfawoX%2BFFwDKzboFeZj7VWP%2BqIpBGERSjNzP%2FUDhj0HtDAWFN7htpOCqCIMFbFUEjqfBbI0f2w8xC3bEZwGI3JCO4T1RAJoh82pk%2B5iMEKcwkmabSEGMp7CR2GcDhsO9q5DWv7gCvnsfagMsF2zDv4jh%2Bdg03UQZ%2BtAGsinQfuc%3D%7Ctkp%3ABk9SR86LmeSRYg
i dont think you can buy them by themselves...
luckily, you can buy a damaged magic keyboard, take its keycaps you need (make sure it has the ones you need!) and fix yours with them :) https://www.ebay.com/itm/225589036088?epid=4037926971&hash=item3486278438:g:yT4AAOSwvu1kbWAM&amdata=enc%3AAQAIAAAA8FO8XME2xI%2FkgVGpqyA4P1g1K9OHz7BJ%2Bf7Tg%2BgNOc8euBx6bTHwdY33Yk3roH8dzrCDQ0TB1qq%2FrhqNiHllFkMbVoI2ryUj0fjBJgAoVGI9RgKZGH4HqloMzygH%2FJsKclgHDpxCi6lUs8JSl7m4hezo%2BalQPbZV1o%2BRNRqHfAMEHHykrXxGk6I%2BYPPw0TkGmJOMn8DK%2F34P%2FDRGbKduXZZBtGZoHHy5er2VEyaXxRxv5tHDPCzl52KwmBhorG9p0qWATtxMhf%2FXM4z6VzXFYyUfqtAJuR4g7MB8baSpCtPzTgTxWMtAmzrgufM%2BnD3LyQ%3D%3D%7Ctkp%3ABk9SR9rijeSRYg
or white keycaps: https://www.ebay.com/itm/154978207460?epid=16045954819&hash=item24156bc6e4:g:oYMAAOSw~i1h7dPl&amdata=enc%3AAQAIAAABADv0vOqjwECwlZ7UXmden5lRJS9LH7mLS4IbXvPyPCTfK7HND3jG3mtLNKumA6ixNQLKtOYFrE1RMgq%2FWM0OSyFBXqojop6bSp1cUym7sDtK7Df8E2mH00VtpJf2%2FTpffxfZ%2FQFVjRmv42Q2tUmCaL4zl5g%2B5xJVAOWGcCPmIq9QtfawoX%2BFFwDKzboFeZj7VWP%2BqIpBGERSjNzP%2FUDhj0HtDAWFN7htpOCqCIMFbFUEjqfBbI0f2w8xC3bEZwGI3JCO4T1RAJoh82pk%2B5iMEKcwkmabSEGMp7CR2GcDhsO9q5DWv7gCvnsfagMsF2zDv4jh%2Bdg03UQZ%2BtAGsinQfuc%3D%7Ctkp%3ABk9SR86LmeSRYg