Not something to sit at for hours at a time, unless you want a cheap way to lose your hair, but the bedlam cubes should keep you stumped for many of hours, and at that price they are a bargain. Grab a couple and keep them for christmas gifts.
If you vote cold because they are cheaper elsewhere that's fine, but please post a link too. For the official cubes of course.
Link takes you to 3 models that were in stock for the price stated above.
I recommend them, and once your done with it, if you ever are, pass it on to friends and family and ruin their life too.
"The Bedlam Cube is the ultimate thinker's puzzle. All you have to do is put the pieces back in the box. This may sound easy, in fact it is extremely difficult. There are so many combinations in playing this puzzle that attempting it at random could take months - even years. It is only through practice and familiarity of the pieces, that you will learn the secret of the Bedlam Cube.
It has been devised as a personal challenge - a puzzle with thousands of solutions which is within everyone's capability to solve...eventually. 13 Unique pieces form the puzzle with 19,186 solutions."