Cost of Replacing Logic Board at Apple Store

At the current moment, my 13" macbook pro no longer recognizes the wifi hardware. Running OSX 10.10, I thought this was the root of the problem. Support helped and solved the issue but it quit the minute I hung up the phone. It is possible that I will need to replace the logic board in order to get everything working again (although I may just buy a wifi adapter) and was wondering what the cost of replacing a macbook pro 8.1 logic board is, just so I don't have a heart attack in the store. Thanks.