Certificate of naturalization

[immihelp]

I became US citizen on February of 2006 (my 2 kids were 10 and 15 years
old), got my Certificate of citizenship at the same day and were
explain that my children automatically became US Citizens.
I ordered US Passports, which we all have now, but I am the one who have
Certificate of Citizenship and I would like to receive Certificates for
my Daughters, who are now 12 and 17 years old.
I read on your web about "N-600" form and the Fee is $460 for each
application. I am a single parent, who can not afford that fees.
I would like to know if it is the only way to get Certificates fro my
children or I do have another options to get it Free.
Also, please could you explain to me, what will happen if I will not
apply for Certificates now, is it requirement?

Thank you very mach for your help,
Regard fully,

[immihelp]

If you want those certificates, you have to pay those fees

Those certificates are not required. US passport is a proof of US
citizenship.