So you've never looked at buying a GPU in this century? The top tier GPU has always been £700 for the last few decades. This is nothing new. It's obvious that you pay a premium for the best, while everyone else either buys mid-tier or the previous gen top tier; the 980ti is a bargain right now.
Yes the 980ti is a bargain right now if you keep your eye on S/H prices you can pick them up for close to £200 and if you are ok with Sil two cards will easily beat 1080ti and for less then £500.