Well I have the Rubik's XV and Rubik's pyramid. The XV is a pretty
good puzzle (ie., I haven't solved it yet after trying for an hour or so).
The pyramid is essentially a Pyraminx. The only complication beyond the
Pyraminx that the Pyramid offers is that the vertex tetrahedrons can be
rotated such that a useless color shows and a necessary color is hidden.

The solution becomes trivial once you have solved the Pyraminx. This
seems like a good place to save your money.

Ronnie