DNA Gender blood test?!

Jennifer • 37yo Married mama of three little boys 10,8, and 2! Trying for our #4 caboose to the family.
Has anyone ever done this "new" blood test for genetic abnormalities and gender??? A friend was telling me her sister had it done at like 8-10 weeks or something and found the sex out early! Another friends said the same thing but since no one knows we are pregnant I just wondered if anyone has had it done?! How much did you have to pay out of pocket?