So what's my ps4 worth if I trade it in when the neo comes out?  Or now just out of curiosity?  

If i skip the middle man and just sell it myself what can I expect to get for it?  1TB HDD will be in it.  

I have a 1.5TB but I'll swap that into the neo. 

Typically Gamestop will give $200 right now for it, but for the Pro release, you'll probably only be able to get $150.

Shouldn't GameStop answer your first question?? EB Games here already listed their trade in deal for the PS4 Pro and the event happened while we were sleeping

You'll have to pay to get rid of it.

So hopefully I'll get $200 for it when I sell it in November directly to a buyer.  The 1TB HDD should be attractive. 

sell it on ebay, you'll get more for it

gamestop has it for $125.00. "best value"

http://www.gamestop.com/trade/quote/ps4/consoles/playstation-4-500gb-system-black/114375

This is why I sold mine when I did. I got pretty much full price for it, if I had waited I would've gotten $125 from Gamestop or had to put up with the hassle of EBay. Screw that.

it won't plummet completely because the old PS4s will be completely valid, at the same time with the new PS4 being 399, no one is going to pay more than 200 bucks for the older, used version. So not worthless, but there will be a noticeable drop in value.

This is good, it will allow people who don't have money better access to games, and people who can afford it a better experience.

I checked last night. Game will price match and give me £200 for my 1TB Darth Vader PS4.

If I sell on EBay I can get more.