给国内父母办移民美国： IV processing fee 是多少?

HI 8 老师： 正在给国内父母办绿卡来美国， 提交了所有文件，付了AOS 费用，  但是从来没有收到 IV processing fee invoice.

 got instruction email yesterday ask me pay IV processs fee, but it didn't say how much it is:-))

can u please help confirm it is $325 or ?

I plan to send fee by mail.

Thanks a lot for reply.