It's been a while, but I looked into a few of them at one point (want to say around 2013-2014?). The one I can still recall the details of had a $500-$750 limit on the purchase price, the payments were auto-debited weekly (mandatory), and you ended up paying around 2.5 times the original purchase price. The payment schedule was weekly payments for something like 12 weeks.

And that was a fairly benign one. Some, especially the ones that allowed for higher dollar amount purchases, were practically usury.

The whole "buy now, pay later" industry is entirely predatory.