Having tried 3 times, 10 hours total, searching for my P3P, I'm giving up.  The drone battery went critical and crashed into heavily wooded area after 16 minutes 32 seconds.  Battery was at 98% when flight started.

Having given up on trying to find the P3P I was thinking about buying a P4.  I see some selling just the quadcopter without controller.  Since I have two controllers for my late P3P (original and upgraded one with extended antenna setup), I was wondering if the P3 controller worked with the P4 quadcopter.  I know the batteries are different.  Do P3 and P4 use the same AC adapter / charger as I have two of those as well.  I'm looking to minimize my loss having spent close to $1,600 on all the P3 stuff I bought.

Yes you can link or bind the P3 control with the P4, some even say the P3RC is better than the P4 RC...or even better, bind the Inspire RC with the P4. But to minimize I think you can purchase the P4 without the RC, I don't know if you're really saving much by doing so. If I were in your boots I would buy a P4 with the RC, keep the P4 RC all stock and modify your P3 RC with a better antenna (DBS ItElite) and then use it and keep your P4 RC as a back up as you never know when you'll need one! ;)

You can just a Phantom 4 from  dealers online (much cheaper than official price) and sell your P3 RC