Open an orphanage next to a fertility clinic. The walk-in traffic will be great. You'll sell so many orphans.

No, the point isn't to pretend they are babies the couple made themselves. Just that being next to a fertility clinic will mean you'll have a lot of people coming by who want kids but can't have them. So they are likely to come in and look around. And if their treatments are failing or are just too expensive, buying from the pre-owned lot may start to look appealing.