Yeah, you can make one for cheaper only slightly though, but it only makes sense if you use it often enough to make 5-6.
-Cheap - under $15
-Easy to learn for beginners
-Easy to create a new routine/presentation for
-Strong effect, very visual
-Great trick to learn how to actually present magic because it's so easy, yet so strong
-The concept will give you ideas for other, smaller applications of the principle
-Requires you to carry a gimmicked deck that can't be reused for much else.
-Been done to death - everyone learns/sees it eventually.
So yeah, like i said, definate buy for everyone - It's cheap, easy and a great way to learn all sorts of good stuff about presentation and thinking about magic....