Well I scored today at work.
I spied our quality inspector going by with an old pc on a sack truck heading for the skip.
I pounced on it,ripped it to bits and found these gems in it.
The black one with the fan is the CPU heatsink,the fan fits into the hole you see,but if needs be it can soon be sawn up to fit.
It is 125mm long,57mm wide and stands 35mm tall to the top of the fan.
The other two came from the power supply.
They're 75mm long for the biggest and 55mm for the smaller.Both are 55mm wide and cut from 3mm Ally plate.
I reckon a pretty good heatsink can be made from some of these bits.
Miggers