recording equipment recommendations for music

Can anyone recommend a basic minimal set up for recording music with Garageband? I expect either to be playing piano and singing, or playing guitar and singing. That's simultaneously, so expect to need two mics. I am talking about a baby grand and an acoustic guitar, no midi's or pickups. I already have the Macbook, piano and guitar but assume that I have nothing else. What mics should I get? What other equipment? Remember, I am looking for basic and minimal. Thanks!