I have a friend at work who makes knives as a hobby. When I discovered this fact, I immediately told him we'd have to make an arrangement for him to make me some batarangs. The guy is so non-geeky I actually had to explain what a batarang was! Anyways, whenever we'd get to chatting about new knife projects he was working on I'd casually mention that he needed to let me know how much it would cost to get a batarang made.
Well the other day he not only surprised me with one fully functional throwing-star style batarang...
...but he surprised me with THREE! To top it off, they were a gift and he didn't even charge me for them.
These things are so cool it's almost a shame to throw them around. I want to frame one of them or make an 'In case of emergency break glass' type display or something. But I have tossed one at a piece of wood and if you get that tip to land just right it sinks in pretty darn good.
I believe he said they were started from a piece of saw blade metal, so they are nice and sturdy considering the relative thinness of the metal. A template was drawn on and he ground them to size and gave the blades an edge (although he didn't sharpen them so I wouldn't cut myself open.) They were then painted with some high temp paint for durability. He said they were pretty simple to make and if you have a grinding wheel (I don't) you could make them quite easily and inexpensively.
So if you are so inclined - go for it!