Hence the paucity of hard data released to the public; the organisations have first dibs on the data to make their money back through publications and in attracting research funding.
As an example: http://www.mps.mpg.de/1979387/MPS-Beteiligungen_an_Rosetta
Basically, ESA provide the bus on which the science kit rides.
As an EU tax-payer I've raged against this in the past but that's just the way it is.
Source: direct question on this matter that I put to an ESA PR at a public lecture about Rosetta.
Edit: most of it will be, not everything, as I've just found out.
As to the project, the cost (open to correction by all means) was 1.4 billion. Downvote if you like; evidently this is my big mistake for not understanding that facts are apparently unwelcome hereabouts. If people assume that by mentioning this sum I am necessarily disapproving of the project then they are simply wrong and indeed had not one iota of evidence to suppose that. Now I know better - 'I must not mention the cost in case something thinks I am moaning about it'.