Take your pick...
Berbatov to United for £30m (9th most expensive transfer of all time)
Robinho to Man City for £32m (7th most expensive transfer of all time)
Shevchenko to Chelsea for £30m (10th most expensive transfer of all time)
Shaun Wright Phillips to Chelsea for £21m
I reserve judgement on Aquilani, Benzema and Kaka for the time being, they are young enough and good enough to turn things around, but it doesn't look too good at the moment.
But seriously, half of Man City's squad is full of players who cost way too much, have limited ability, and will never justify their price tags, such as Jo (£18M), Balotelli (£24m), Carlos Tevez (£45m), Lescott (£23m), Santa Cruz (£17.5m).
The above players would be pushing their luck at half their price.