Usually if you can find a local photographer they'll do them for nearly half the price on how much you'll pay if you go somewhere. I had a girl offer to do mine for 40 to 50 bucks, but i do believe they generally cost about 100 to 150.
One of the reasons I never bought any. I just bought a couple bigger shirts and wore workout pants that I had prior to pregnancy. The only thing that really got bigger on me was my waist up to my breast.
If you want a good photographer it will be 150+ more than likely 250+ in Chicago... But if you aren't super picky and won't be hanging them around the house or making a book out of them, you could possibly find someone new who can do a good job for 100