Adjusting cable for a crew seat [allows the seat to slide back and forwards]. This is a 50cm sheathed cable, nothing high tech, with a solder nipple at either end. £360.... and they break for fun. Bike shop here we come!
Generator brushes - a couple of bits of graphite with a spring on one end. £600....
I remember in the mid 1980's some [obviously] very bored Bristow Eket engineers worked out that it would cost approximately 4 times as much to build a Bell 212 from spares as they were to buy; rather a lot when you consider the new cost includes paying the factory guys to build it!