A Chladni plate does nothing on its own. The WA-9855 Wave Driver is the voice-coil shaker that couples a signal into the plate, and PASCO's page is candid about what it demands: an external function generator supplying at least 8 V at 0.5 A, with a maximum draw of 1.2 A AC. It weighs 1.8 kg and measures roughly 16 by 11 by 12 cm, with a built-in rod clamp and string holder so it also drives strings for standing-wave work.
As with the plate kit, no price is displayed; you request a quote.
For anyone building a rig from parts, this is the component to think hardest about. A cheap audio exciter glued to a plate will get you patterns, but a proper driver with a rigid mount and a stated current rating is what makes results repeatable from session to session, which matters if you are photographing modes rather than just showing them.