I am by no means an expert on the old 3 speeds but I see them on CL. A Raleigh like yours, very solid bike. Build to last forever. I think $100 was a fair price considering the work it needs. Get the IGH sorted out before you do any riding, don't want to ruin the hub. Could be a simple cable adjustment.
Fully overhauled and ready to ride, maybe as high as $200? I could be way off, so don't necessarily take my word.