I just took the plunge an bought this rather nice telly today. The cheapest I could find is £499 from online retailers.
I managed to haggle a bloke in Comet down to 489.99 so agreed the purchase, when he ran it through the till it came up 449.99 so thats all I paid! Also Panasonic are running a promotion which this telly is a part of where you can claim two free pairs of active 3D glasses which is not to be sniffed at.
Also try finding any 42" Plasma that is full 1080p with Smart functionality, Sd card and Usb slots, hd freeview with recording capability, 3d capable and able to convert 2D signals to pretty impressive 3D output for this money.
I must say the picture quality is amazing, only the reflective screen lets the side down.
Could be a nation wide pricing error or just my store so please go easy on me.
All the best