We had it done with both children and used Stork Snapshots the first time and then Golden View the next. Both places were about the same. The only advice is to wait toward the later end of the pregnancy to get it done so that the baby has more fat and takes a better picture. With my first baby, we were so excited, we went as soon as we could (somewhere in the 20 something week, I think) and my daughter was so skinny and strange looking, sort of distorted, I was scared. She did not look anything like her 4D ultrasound when she was born, thank goodness!
With my son, we waited until the last 2 weeks we could do it, and he took a very nice picture.