It's a bargain in terms of the fee to Man City, but overall, it's not that much of a bargain.
£5m fee to Man City + £5m signing on fee to Ade + £110,000 a week wages.
That's going to add up over a 3 or 4 year contract! When you consider there is no real re-sell value, it's not particularly cheap!
Of course I meant a bargain relatively! If we signed Llorente or Damiao they'd probably want a similar wage packet but would cost 20m+. The only downside of Ade is his re-sale value, or lack of.

