Requesting an NSO copy of your birth certificate costs Php 140 in SM Business Centers, same amount if you get it from NSO offices. However, SM charges a Php 20 service fee on top of the price. So that makes it Php 140 + Php 20 (service fee) = Php 160 per copy in total.
I strongly recommend you to purchase through SM. The Php 20 service fee is much worthy compared to the long lines and heat if you take the long way via the real NSO offices.
Jemima Hezekiah