The ones I saw were at WEX, and they all seemed to come from the Norwich store. The really nice one (condition 9) at £499 (reduced from almost £600) didn't hang around long. But they had three or four and were all below £500.
I shall probably end up getting one someday, but I'm not 100% convinced that a range-finder style isn't better for me, so I'm going to play a little with my GX85 and see how I feel.
Those are/were good prices, assuming they were perfect and had a low shutter count, I assume they did not have lenses?
The second part, although the main specs are similar, the G9 ans GX9 are quite different to use.
The mode dial on the GX9 is small, and you would not be changing it with winter gloves on

The viewfinder is fine, but nothing near the G9.
The memory card in in the bottom with the battery, the G9 has dual cards on the side.
The G9 has mic and headphone sockets
The G9 has two very useful function button next to the lens near the finger grip
The GX9 does not have a remote socket, so you would have to use a mobile device
The on/off switch on the GX9 is backwards like most of the older Panasonics, the G9 is logical
The G9 burst speed is double then GX9, and can take more shots before buffering slows it down
The LCD on the GX9 tilts up and down, but can't face forward or sideways
The GX9 has a much shorter battery life
The GX9 has about the same menu structure and features
Surprisingly the GX9 doesn't feel unbalanced with the 100-400 lens on it
The GX9 also has front and back wheels, so easy to use on manual
The GX9 has a dedicated exposure compensation dial under the mode dial, very useful
Although they are similar many ways in performance, there will be a definite choice between them depending on what I want to do.
Just some initial thoughts, not quite had the GX9 a week yet!