I bought these white (swivel, with red cushions) tulip chair reproductions from eBay - they're new, and so far seem great. Search Tulip Chairs", I paid $275 for a pair, plus about $80 in shipping. They came in just 2-3 days. The FedEx label said they came from : I&L Distributing Inc., 544 Park Ave., Brooklyn, NY 11205.
A friend of my husband pointed us to the other chairs, the "Case Study" fiberglass side chairs available in 12 colors @ $239 plus $35 shipping. I've certainly seen both of these styles (and there are more on the website) on ebay - these look to be terrific reproductions. From http://www.modernica.net/.