How old do you have to be to get a tongue piercing?

You have to be 18 to sign for yourself for any piercing. If you're under 18, you have to have a guardian signature of approval.

I have a question how much does an industrial cost here??

Under 18 you have to have a parent, 18 you can do it yourself.

To add to the above, the parent or guardian must show ID/proof of guardianship if not a parent