Put it this way, If I had £500 to spend and wanted a full frame DSLR (body only) I'd seriously consider putting a £150 or so to it and look at a mint-ish, low-use Canon 6D Mk 1, which should have better low-light performance and image quality than the 5D Mk II in my opinion. Even if you bought a 5D Mk II for £400 I think it would still be a bit 'old hat' by today's standards. Don't get me wrong, a 5D Mk II can still produce nice looking photos... but so can a 1924 Kodak Brownie box camera given the right subject and lighting conditions! Anyway, it's entirely up to you, but at £500 I think you aren't that far off being able to own something a 'camera generation' newer. I hope this is useful, but only you really know your camera needs, so perhaps have a good think about it and do some research before you decide on which camera to buy.