OK, happier now.
well you need a 20:1 steo down transformer, if you are talking about 'transformers' as opposed to transformers.
http://www.maplin.co.uk/chassis-mounting-transformers-454504 N64JB would do you, 2 Amps max at 12V and then build a rectifier on some breadboard.
I've just brought a noctua which claims to be 0.6W at 12V = 0.05A and it claims that it really low power, so lets say that normal is 2W, = 0.16A. so for your 4 fans you need about 0.64A total.
what I don't understand is why the halogen transformer couldn't rotate them, you were connecting the right pins weren't you, or are we talking about big molex connectors and not little 3pins? the 3 pins one of them is for a sensing circuit.
I don't see why this wouldn't work
http://www.maplin.co.uk/low-cost-6w-multi-voltage-power-supply-226 not sure if it is rated for 24x7. Unless the 'chopper' type systems being used in cheaper lighter power supplies don't allow fan to function, probably the electro magnetics.