When I was interning in the architecture and design department at MoMA last summer I got to take occasional and, for me, completely thrilling short field trips around New York (and, once, outside the city). The first was a visit to Mondo Cane's warehouse, where the owner, Patrick, had filled a circuit of fifth-floor hallways with children's chairs. Dozens of them! Spanning a century, some looking like their parents (little Bertoias and Thonets), a bunch I'd never seen, and all up to your knee.
It looks like some are for sale at Partners & Spade. If I had a few hundred dollars kicking around, I'd definitely consider adopting one or two.