I think the reason for the price is that the camera is now a clearance item, having been replaced by the GX-20.............this retailer might not have too many left on the shelf.
I think also that the battery grips are now a bit like hens teeth. I think if you can find one it would be about £100/£120.
A battery grip really does help if you have large hands, gives the whole thing a bit more "body" to hold onto, and of course when you turn the thing on it's end to do a portrait style shot, there is a second set of controls on the grip lying under your thumb.
What makes it easy to use is that as well as the options for manually setting apertures/shutter speeds etc., it has (unlike the Pentax) the usual array of "modes"...scene, portrait, night, macro etc etc which you can set and then the machine optimises the settings for you. Not for me, I like total control, but great for the less experienced.
If you can get a 50-200 lens (yes a 4x zoom) for £70, that is a bargain (again it is a Pentax lens under a different name) and of course a good addition to the 18-55 (3x zoom) that comes with the camera.
Calm down now, Xmas is past and it's not your birthday yet
.......don't know how long that offer will last though if they are shelf clearing.
edit..............TD posts edit to take out his last edit....