Where Can I Buy a Replacement Keyboard Key - Surface Laptop 3

Hi Everyone, the letter K came loose on my Surface Laptop 3. Because the key became fully loose it isn’t covered under Microsoft Warranty - who incidentally also managed to lose said key when the device was back with them. Their only option for me is an out of warranty replacement - which is a small fortune. I have tried many online retailers but noone seems to supply replacement key sets for this model. Be glad of any suggestions or ideas?