I Can Play Guitar Game Price

My son got a green day rock band game for his birthday from a relative ( Who is a bit older, and didnt realize I needed special controllers to play it). I have the guitars, but no mic, or drumset. When we try to play the game, it wont let us in, without having a microphone…I’ve priced them, and found them for around 25 dollars, which isnt bad…but I’ve priced the drums…and they are a BIT out of my pricerange for right now, especially with christmas right around the corner…I would get him the drumset for christmas, but I’ve already spent so much on his gifts that i have so far, that it would break me…its something I’d much rather wait on until after christmas. So, Can I play the game, without the drums?? 🙂 Thanks!