From what I see, the guy knew what he wanted his set to sound like and bought what he needed to get that sound. I'm sure it sounded like rolling thunder when he played Proud Mary. I see the Ghost pedal and the HH pedal that looks like Ludwig speed king and the 14" tom. I see the normal light rust that shows that this kit has been around and not just stuck in a closet (though it is probable that the kit has spent some time sitting alone). The heads look decent so the resonant heads may not need replacing.
I think you are very lucky to have a chance at this set. Go buy a lottery ticket today, that way you won't have to worry about the price. If you can get it for $1500, your luck is still holding. Anything less than $3000 is worth bragging about.