I found an excellent deal on aliexpress.com. Yong Heng sells direct there. I picked up the adjustable 110V-US pump for $367.16, AFTER shipping. This is a full $100+ lower than amazon, and comes directly from Yong Heng in China (presumably).
http://s.aliexpress.com/7NFrEzER
http://s.aliexpress.com/7NFrEzER