Here is what I have hit on for a simple "expedient" snare that has multiple uses - steel wire fishing leaders. I got a 3-pack at the local Kmart for $1.99, and they have a locking clasp on one end that you can double over and clip to the leader to make a snare. They're also good for fishing, of course, and three of them take up less space in a PSK than a roll of wire.