At that price a replica is cheaper!
Is it about £450 to get a custom CRT made?
Based on devaluation/inflation, £100 spent in 1936 is about £2,000 to £6,000 today? So 17,000 / 4,000 = 4.25x value, not 168x value as might appear.
Somehow I think a 2011 £400 HDTV LCD is unlikely to be worth 4x more in real terms for your (great) grand children.
I'd guess most 1950s TVs are still worth less in real terms today than what was paid for them?