I've bought a Solidtek 6600 recently, and for $40 I didn't expect anything too fancy. But this detail was a bit of a letdown:

As you see, the 'C' can't be pressed as deep as the others keys; it sounds different too. Now, it's technically not 'defective', it works fine, and it's still better than anything that I could get locally. Besides, international shipping would make a return more expensive than straight up buying another unit. Still, it's quite annoying to buy something and find it's a bit 'off' like that.