A note. OpenMerchant was owned by OpenSales, which changed its name to Zelerate, which got funding contingent on 40% staff cuts and changing to a business model involving selling their software for (IIRC) $100,000 a pop.

They are also competing with an old fork of their software on Sourceforge.

I wish them luck in the same way that you wish Wile E. Coyote luck in catching the Roadrunner...