If you own a gun that would be great. If you can afford to buy a crossbow that would be awesome because a crossbow can be used to shot both a metal ball or an arrow. However if you couldn't afford a crossbow, then you can opt to buy at least two high velocity slingshots, several boxes of metal balls and a minimum of 10 arrows.
(you need two slingshots - one to shoot a metal ball and the other to shoot an arrow)
When a marauder with a baseball bat is at the gate you can start pelting him with metal balls just to deter him from entering your house, but if he came with a machete then switching to arrows might be unavoidable.
High Velocity Slingshot = RM13.00 x 2 = RM26.00 (click here)
Metal Balls (100 per box) = RM20 x 5 boxes = RM100 (click here)
Update: A fan by the name of fadz sent an email to me strongly advised me not to buy any arrows from http://lelong.com.my because according to him he had recently purchased RM18.00 x 10 arrows from the seller Josef and was shocked to see that all the arrows he received are uselessly blunt. According to fadz It turn out that there are two type of arrows, one with a blunt point (for playing-playing and target practice) and the other is the sharp one for hunting. The one for sale in Lelong is blunt arrow and is no doubt useless for preppers like us.