Lots of oil and patience is required. I would guess all the milling, drilling, tapping and polishing are what you are paying for. Then there's markup. They are probably made only in small lots, pushing costs even higher, but they sure are purty and permanent.

What are counterweights made of?

Counterweights are typically made of metals – with cast iron counterweights and concrete counterweights being the most often used ones. Steel, titanium, tungsten and a few metal alloys can also be used to manufacture high-quality counterweights.

How a crane is balanced using counterweights?

A counterweight is added to the opposite end of the articulated jib to counteract the weight that the crane will be lifting. ... This is where the tower crane lifts varying weights, building up to its maximum capacity. If all these tests are passed then the crane can join in with the construction process.