Is it worth the money to you, what kind do your own, and do you LOVE how they fit? I tried on a couple pairs of maternity jeans, one from the Gap and one from Mimi Maternity and they were both too short, droopy in the butt, and made my butt look super flat (which I don't have a flat butt). My prepregnancy jeans don't do that to my butt.
Re: If you own expensive maternity jeans ($65 +)
I have a pair of Paige maternity jeans that cost around $180. I'm 5'11, so I had to get something designer in order to get the length. I really do like them and get lots of compliments (some people have asked if I'm still wearing my regular jeans!). My only complaint is that the panel is not very large/supportive. I have to wear a bella band to help keep them up.
I also have a pair of IT jeans from Mimi in an awesome, slimming dark wash. Love them! But that being said, I also have a pair of fit and flare from Motherhood with the secret fit belly that cost $35 and I love those as well. I'm hoping these two pairs and two pairs of black dress pants from the Gap can see me through the rest of my pregnancy.