Step-by-step instructions on how to make a wire armature for a stop motion puppet for around $15 in materials:

16-gauge aluminum armature wire (from an art store or Amazon, not the hardware store)
Epoxy putty (Hardware store)
T-nuts (#8-32) (Hardware store)
Wing nuts (#8-32) (Hardware store)
Bolts (#8-32) (Hardware store)
Washers (Hardware store)
Pre-wrap/athletic rap/sports rap (Sporting good or drug store)
Cotton batting or foam (quilting supplies from craft or sewing store)
For the head, aluminum foil or wood ball (craft store)
Wipes (Epoxy putty gets messy) (Drug or grocery store)

Just about everything here can be found on Amazon if you don't have all these kinds of stores in your area. You can also get animation supplies from stopmotionstore.com.