What do you mean "be realistic"? I am not just making up numbers. The bike I found for my dad was from The Bike Shop, brand new but 2 years old and 50% off
It's a Rocky Mountain FS. MSRP was $3999 and he paid $1999. You aren't looking hard enough if you can't find a good deal on old stock or a gently used bike.
The Giant Glory DH I bought back in the day was also old stock and right around half price.
I paid full price for one of my Trance's but I don't think I'd buy new again to be honest.
These people saying the changes are "DRAMATIC" every 2-3 years, I don't disagree that there are sometimes changes or overhauls (that the importance of depends on the rider), but I would challenge them to blindly ride a bunch of identical models from various years and tell me what year they all were - I would bet they could not.
The OP is looking to get back in the sport with a $1500 budget. You can get some very new, very good used bikes in that price range that are like-new. I don't think he should be ignoring those at this stage in the game.