Value of HP28C vs 28S?

[d b]

Something to watch out for when buying a Clamshell through the internet is to make sure the battery door is unbroken. Many are, due to bad design. Ask- and if you can't get a direct answer then I'd suggest you figure it's a bad deal. Someday, someone will 3d print these but that day wasn't yesterday and it's getting late today.