How much does it cost to repair a key?

I got a new MacBook Air, 13" Model A1466 for Christmas this year. I have accidentally, cosmetically damaged 3 of my keys. The

"Delete"

"\"

and the "return" key.

I'm trying to refrain from freaking out because I have no clue if I can repair these keys myself or if I have to pay someone at the Apple Store to do so.

If I can replace them on my own, how much would it cost? If I have to go in and have this repaired, does anyone know how much that could cost?

please help, Thank you