How does going about a blood test work?

Jess • soon to be first time mommy - 2016
I'm ten weeks and one day. My boyfriend and I really want to know the sex. We know his relative took a blood test and found out the sex. Its apparently out of pocket costs with your own private insurance hopefully covering some of it. Is this correct? Where exactly do you go or is this done with your obgyn? Please let me know your experience for any of you who have gone through this and was it accurate. Thank you!