well I've had a set of cheap coilovers on my ride for 4yrs now and haven;t had a problem w/ them at all... One of the main reasons that alot of the coilovers aren;t any good is because of the amount of coils that are used on the springs...

You will notice some of the cheap companies don;t have as many coils or they are really spread out which in turn will mean a pretty poor ride... I have known peopel to have and ride on DZ CO's and they liked them and they had a decent ride...
Just my $.02...