Here is what I use for targets the first one is one I made out of an old morrell yellow jackets target and a cheap wally world foam target. I just took the two types of material and put 1/2 inch thick pieces of wood on top and bottom and then duck taped the whole thing together. It is light weight and works great.
The next one didn't cost me anything because I just happended to have all the materials laying around.
I made a wooden box frame outta 2x4s covered the front and back with old carpet and stuffed it with old drop ceiling panels and foam. I don't know the exact dimensions but its a little over 6 feet tall by at least 3.5 feet wide.
as you can imagine its a little heavy so I had to make a chassy with wheels for it so I could tip it down and move it around with ease.
I aslo added supports to it that fold up so you can move it. These supports make it so it will stand up on almost any terrain weather its level or not. They can fold either behind or in front of the target.
by the way the target is lopsided in the picture because when not in use I lay in on the ground in that spots so to take these pictures I just picked it up real quick.