Q: change my macbook keyboard?

Yes the KB can be replaced. I can't give ny price since you did not specify your model Mac

- You can do it yourself if you are up to it. See:

https://www.ifixit.com/Device/Mac_Laptop

That link has links to replacement parts

- Make an appointment at the Genius Bar of an Apple store to find out whatr Apple would charge

  Apple Retail Store - Genius Bar

https://www.apple.com/retail/geniusbar/