Yeah you do have to pay for them. They differ in prices depending on what package you choose. It's best to go between 28- 32 is what the tech told me. She said if you go to early they look like a skeleton still then if you go to late getting a good picture can be iffy because they don't have as much room to move around.

@williamsbaby2016,

if you go to a place yes I usually ask the sonographer at my ob if she can do a 3d when she's doing the sonogram and she says no problem and does it

Do you have to pay for 3D/4D ultrasound and how many weeks do you have to be?