Another cool find. The Ripple chair by Ron Arad was introduced in 2005 but has such a familiar, natural shape that you could be forgiven if you thought it’s been around for much longer. :)
The chair is made of plastic with metal legs. An added bonus: they’re stackable!
At $350 (plus S&H) they’re neither overly expensive nor cheap… (considering other modern pieces regularly sell at around the $1000 mark)
Check it out at the MoMA store.