You talking about the old Superdisk? Looks like a floppy, acts like a floppy, stores 100MB+? They'll be hard to find nowadays, if at all (try Ebay)
Or are you talking about the "fatter" floppies which are really ZIP-disks?
They come in different flavours, 100MB/250MB/750MB but are not interchangeable on all machines. IOMEGA makes them, are still for sale in most places. 100MB disk about $10.-
Have you considered a crossover network-cable? Needs a Network Interface Card (NIC) in each PC. Cards about $ 12.- ea. and cable about $7.-. The needed software is part of Windows.