Early Gender Ultrasound (15-17wks)

Br
I was curious on what experiences you ladies have had with this. I really wanted to do a gender reveal for Christmas and for me to be able to do that I'd have to pay ($75) for a session to get it done. This is outside the OBGYN.. and it's a business that does 3D/4D for families. My OB will not do another US till 18-20wks and that's well into January for me. 
Was it US correct? We're you able to see gender? 
Etc..
They give you a free session if baby doesn't cooperate but after that I think you pay again (which I cannot afford). 
Thanks in Advance💕