Greetings from K-Town

I purchased my 04 from Toyota in May 2010, it was already dropped with 18 inch wheels, I was experiencing some shaking and vibrating of the steering wheel around 50+mph. I take it back to the dealership thinking it's possible alignment issue, dealership calls me back and tells me that they can't put the truck on the alignment machine because of the aftermarket components with the dropping of the truck, tells me that they dont have the correct specs to punch into the machine to align the truck. So I end up taking it to a custom shop which tells me that whoever dropped the truck didn't do the job correctly, they're telling me that's the reason for the shaking and premature wear on the inside of my tire, they suggested that I return the truck to stock height. My question? Does this sound legit as far as reason why my tires are wearing prematurely, and if so how much will conversion to stock cost?