Mainsprings for American made antique watches experienced a 2 to 3 times price increase
recently, owing to the fact that the swiss factory making them has decided to reduce, or in
many cases, cease altogether manufacture of these springs.  The price has now settled
down a

I still recommend replacing the mainspring as part of any service, especially if it is an older
blue or set spring.

Used "blue" Set Mainspring
New mainspring