Central Air Replacement Costs

I reached out to a fairly big HVAC contractor in Brooklyn about replacing/updating my 15 year old, 2 zone, central air system. The quote came back at 36K, double what I was expecting. This would involve all new hardware, 2 – 2 ton compressors, plus new everything else except ducting. Are my expectations skewed, or was this quote inflated? I’m in the process of getting additional quotes.