I paid $89 but she gave me a bit of a discount since I drove 3 hours to get there. You need to ask, though, because they are not all certified techs.....there were two different places I checked into and only one (the more expensive one) had a licensed technician doing the u/s. It may depend on state regulations.....?
I went in at 19 weeks. They recommend 26 or more so you can get a good face shot when the baby has got some fat on him/her, but I think a lot of places will do gender with high accuracy at about 18.