Some drums, like some horses, move well with others by blending with and complimenting the flow of those moving nearby. Other drums, like wild stallions, overwhelm a group and are best ridden on a solitary journey. When someone comes to buy a drum, I suggest she go into a private space with all the possible drums and drum stick combinations, and go riding. Playing a drum and riding a horse cannot be understood through talking, but only through doing.
And just like some horses do, a drum can pick us. We may have our eye on a big, powerful shamanic painted drum--one with lots of vibration like rippling muscles across its surface--and a sturdy little Welsh pony of a drum keeps calling our attention back to its practical size and steady voice, indicating that our enthusiasm for drumming in sweat lodges or on backpacking trips will be well met.
Perhaps the best advice I can give if you are planning to buy a drum--is to know yourself honestly and well--and then to not have a plan. Whether you read oracle cards, work with dreams, meditate or contemplate--explore how you really want to be with a drum. Then just be open and trust that like good horses everywhere, your drum will sense your presence by the gate, and will come slowly toward you of its own accord. I believe all spirit companions come to us like that. Of course, it also helps to ask a cat.