P4 Advanced & P4 Pro are great drones. If you like them.... its hard to beat. The P4 Pro has more collision sensors and adds 5.8ghz which I use to stay clear of interference. Prices have fallen on these drones and you should be able to find good used ones between $500-$800.
The P4 Pro V2 would add more range and is compatible with the DJI Smart Controller if that interested you. Other than that, its the same as the P4 Pro. You will pay $800 to $1200 typically for a good used one of these.
If you are looking to move into the future..... The DJI
Air 2s is amazing. Lots of range, great camera, reasonable cost. $700 to $1000 used. $1000 to $1300 new depending on package. The absolute best deal out there is the DJI
Air 2s Fly More package with RC Pro screen controller @ $1750. The controller alone costs $1200 so it is a heck of a deal.
My only disappointment.... having owned all of the above drones is that DJI has taken away some great automated features on the newer
Air 2s. Course Lock, Waypoints, Terrain Follow and a few other modes that I use regularly on the
Phantom 4 Pro are missing.