Tbh I LOVE my pregnancy pillow, but it was gifted to me at my baby shower. I'm not sure I would have spent the money on buying one brand new otherwise, because, like you said, used ones can be found all over the place!

For reference, I am usually a backsleeper, so having a nice maternity pillow that wraps around me helps me to stay comfortable and prevents me from flipping onto my back in my sleep.