I don't think they sell the keys separate and you wouldn't buy a new keyboard, either.. you'd be sending it in or buying a whole new deck for $80-100 US.
The key looks like it's the same size of the Strg key below it. If you can find other keys the same size, keys you don't use.. I'm sure you can sacrifice something on the keyboard temporarily until you find a fix.
Also are you sure the key is broken, and not just detached? The way to place it back on is .........
put the bottom of the key in first in the middle,
slide it down so it hooks onto the notches you see on the scissor clip at the bottom,
then firmly press the key down to clip it back on.
Otherwise, please report back what damages you sustained.
❤