Can I buy and replace my "airport chip"

Yes (or probably, depending on your comfort level with opening up your machine) -- and ifixit probably has the guide to do so! You don't mention which model of Macbook Pro you have -- but here's the Airport Card replacement guide for the 15": MacBook Pro 15" Core Duo Model A1150 Airport Extreme Replacement

If you poke around the site, you can probably find a guide for your model.

UPDATE: It's worth noting that it's not as easy to replace the Airport card in a Macbook Pro as it is in a Macbook. The repair is listed as "moderate." I'd definitely recommend reading through the guide thoroughly before attempting a repair to be certain you're comfortable with undertaking it.