how did you get a 3D scan?

Samantha 💞👶🏽👶🏼💞
How do you all get 3D pictures? My MFM has the capability of pushing a button on the ultrasound machine to show us 3D, we ask at the beginning of our scans but they always forget. I don't want to be pushy or demanding but I really want to see my boys in 3D before its time to welcome them. We only have one private place in my area that does them but it's $150 for a 15 min session and I can't fathom paying that when I can get it done at our specialist office. Please Help me figure out how to get them without sounding pushy or demanding.