I've actually had better luck getting cheap tickets for this show than any other regular show on Broadway. I saw Cursed Child twice in two weeks for just $20 a performance and I had only bought the tickets 5-7 days prior to each show date. Because this show offers refunds to ticket buyers, I'm finding last minute $20 tickets available through their site (presumably having been rereleased after a last-minute cancellation). Keep an eye on that week of performances and you might get lucky.
"Mostly, I loved the size of these people's emotions. Nobody has emotions this size anymore. Outsized emotions. Operatic emotions. Kushemski and Vanda are like Tristan and Isolde, they're Paolo and Francesca. Nobody's in total thrall like this anymore. Nobody's overcome by passion like this, or goes through this kind of rage." Thomas, Venus in Fur