Companies, such as Alstrom and Bombardier, charge over £2m a piece for a tramset - that is what Manchester is paying. They are seriously complex, that have evolved over lots of time to what they are now. Trams are not cheap and quite a few eco hybrid/electric bendy-buses can be bought for one tram.
From the 1st Oct 2008 new health & safety regulations applies to light rail
(trams) as well as heavy rail (trains), so the safety levels are higher and hence
more expensive.
Whatever figures they give for tram systems to be built, it will be a hell of lot more.