It's not 26" or step through, but the KHS Green Delux has most of your other requirements: GREEN 8 DELUXE | KHS Bicycles. It's a steel frame, upright riding position, with disc brakes. They also make a step-through version, the KHS Green 8. I wonder if you could put a disc compatible fork on it. That would get you everything but the 26" wheels. I think the Delux is about $1000.