yeah I generally just use The Cubicle, SpeedCubeShop, or Amazon,... then I check eBay if I can't find what I want at the first three.
Though since poking around that HKnowstore.com site I'm tempted to try and order a couple from them. They have some odd stuff I haven't seen before.
to update the thread, the V-Cube 5x5 and 7x7 are still incredibly hard to turn. The 6x6 broke in, as did the 8x8. They're not 'fast', but they're loose enough to solve easily.
all but the 5 and 7 are pretty good. Not 'speedcubes', but solid little puzzles with a nice clacky 'Rubikesque' type of feel.
the 5 and 7 are still painful and I have no idea how to get them to loosen up.
....for the sake of completion I admit being tempted to get the 9x9.