bmw 525d - bmw 525d turbo failure - bigmennie

Hi my turbo has just gone on my 03 plate, e39 525d it has 107,000 miles on it full bmw service history and iam not happy as i feel it is abit premature i always let the turbo wind down as well before turning the engine off, can anyone tell me if they are a common fault on these or when they should normally go, it hasent gone completely the bearing has collapsed inside but dident drop its oil, and can anyone tell me where i can get a turbo cheap either reconditioned or brand new.

Thanks

Jason