Among the whizzy gadgets unveiled in January at the Consumer Electronics Show in Las Vegas was the Elvie Rise, an automated baby bouncer that transforms seamlessly into a bassinet. The device, which costs $800, sold out even before it was formally released. Parents who missed out can instead opt for a SNOO, a rival bassinet that rocks its occupant back to sleep through the night while dispensing white noise—and which costs around $1,700.