What soundproofing foam should i buy for my room for recording drums?

do you want to "sound proof" your room to keep the neighbors from hearing you or are you trying to cut room ambiance and external noise? Drums are so loud compared to the noise around you that unless the room has an echo. I wouldn't worry about it. You will never hear any background noise like street noises in the mix. I record drums in my living room all the time and you can't hear background noises unless the drums stop. For softer instruments or voice you need a room without echo or reverb and no background sounds. Good luck.

You need to email yo local chicken farm. They sell foam egg carton foam by the roll. You can get it cheap from them. I paid $10.99 to do my whole livingroom once. It is a 400 square foot living room too