Alexi uses duncans,but he also uses mesa stacks and other $$$$ stuff.
Go for the EMG's and be done with it.

I think zakk wylde is proof that you don't have to have a gazillion dollars of super high end racks and amps to get good tone.Zakks rig is simple,but his sound is massive.

Note that pickups will not make a crappy guitar and amp sound much better though.