best reactive targets on a budget, use color balloons.. You can inflate them to whatever size you prefer. once it is a hit, it pops and disappear - instant gratification.
The only caveat is wind control. You have to make sure it is taped at three locations to whatever cardboard or target holder to keep it stable. If you do not mind a little play of the ballon by wind, that is OK as it will add more excitement to shooting a some what dynamic target