Some have started to pop up on eBay. Here's one:
https://cgi.ebay.com/Loading-Toys-Lifelike-Human-Head-w-Gas-Tank-1-6_W0QQitemZ360204326566QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53ddd9d6a6&BackToListReferer=http%3A%2F%2Fmy.ebay.com%2Fws%2FeBayISAPI.dll%3FMyEbayBeta