Have you seen this ?

[fin]

Am I crazy to think someone would pay £700 for an ex-demo chainset ?   

have a look here
Call me old fashioned and crazy, but it's not even pretty and I've never heard of the manufacturer.

Is this chainset really worth that amount of money and would you buy it ?

I know all about supply and demand theory, but really!
And no, I have no intention of buying.  (I've already got a spare Campag chainset in  the shed     )

[LittleWheelsandBig]

Tune is a very high-end German component manufacturer.  Their stuff is usually exceedingly light.  172.5 mm tandem cranks are pretty specialised, my preferred crank length but not my preferred price.

[rdaviesb]

Tune. Bling, bling, bling. I specified on of these

http://www.jdcycles.co.uk/components/tandem-components--accessories/middleburn-tandem-chainset

and two of these
http://www.parker-international.co.uk/2597/Royce-Titanium-Bottom-Bracket.html

which comes up at near to that price, so all in all it's actually not a bad deal, given that you get everything thrown in.

[Rig of Jarkness]

Be interesting to see if its still appearing on their website in 6 months time !