I am from South Africa and unfortunately cannot help you with the price.
What I can say is buy genuine Nissan head bolts as they are better quality.
One of my head bolts cracked and I blew head gasket. Replaced needed stuff and installed ONLY the one head bolt and reused the other.About 6 months passed and oil got into my radiator fluid.
Investigated and another head blot cracked.

Moral of the story. Don't reuse and buy genuine head bolts.This is a part of your engine where you cannot be cheap.

Guys, My head bolts says 12 ontop.
What does that mean as you said he must use that have a 13 ontop.
I have the GX head with the 10:1 compression.
Is it maybe that I have the deluxe headbolts?
Will they handle the 10:1 compression as I sometimes drive my Datsun hard.I do not want the head flying off due to compresion.