If you feel dedicated, the following store has a supply of the nifty Dogic twisty puzzles:http://www.spieletobs.de
Click "Go Shopping", then "Knobelspiele", then "Drehknobelspiele".
The catch: they only ship COD (cash on delivery) to addresses in Germany. I begged some serious favors from a relative of a friend of a friend of my wife's, and had one shipped to me. No, I can't help you get one.
This brings my collection to:
2x2x2 Rubik's Pocket Cube
3x3x3 Rubik's Cube
4x4x4 Rubik's Revenge
5x5x5 Professor Cube (Meffert's)
Skewb Diamond (Tiled)
Coke Can (like a toroidal 15-puzzle)