You can make your own mannequins for practice by using 3 children's Styrofoam pool "noodles" and duct tape.
Take 2 noodles and cut them off at just about the height of your arm pit. Use 6-8" of the scrap piece and position it horizonally at the level of your hips between the two uprights, tape this in place. The third noodle will make up the shoulders and arms. Lay this one centered over the uprights and determine how broad you want the shoulders to be. Where ever you want the shoulder cut a 45 degree notch on the bottom side to allow for a bend. Place the top of the uprights in the new armpits and tape secure. The excess arm can be cut off leaving the mannequin with just upper arms or an elbow can be made by cutting another notch, bending and taping. If you leave full length arms, a hand can be made by simply making a slash near the end of the arm. You can then make a cardboard cut out of whatever weapon you might want your "bad guy" armed with. Use about 4" of your left over scraps to make a neck, split this downward a couple of inches so it can hold a paper plate (head). The noodles have a hollow center that allows each upright to slide perfectly over a piece of 1/2" conduit tubing that has been driven into the ground.
You can give your mannequin a cardboard breastplate so you can see the hits, or just dress them in some old jeans and a T-shirt for some realistic practice. The noodle cost less than $2 at Wally World and can take hundreds if not thousands of rounds. For about $30 I made a small army of mannequins that we could arrange in countless CQC or hostage scenarios. I will say, don't try to simulate a longer range shot by making a reduced size version, it looks like a kid and makes you feel terrible as soon as you see it wearing a shirt. However, Osama holding a cardboard AK is hours of fun.