3D/4D gender US

Dannishia
My OB is very old school, makes mommas wait til 23 weeks to find out the gender (which also isn't gaurenteed, with the position of baby) and she also uses the 2D US which I know leaves room for error. 
But I found a place about an hour and a half away from my town that does the 3D/4D US for $99-$150 with pictures and a CD to take home. And if by chance they can't give you a 100% gender answer they let you come back for free til they get that answer for you. I asked a couple people, and they look at me like I'm crazzzzy. 
Am I crazy? Or for a first time mother (miscarriages in the past) is it perfectly normal. 
If also like to be able to have the 3D/4D US in the baby's book, since my OB doesn't offer them....