eBay would provide lots of PAL A600 units (complete), however motherboards only are a bit uncommon.
There is an auction
right now for an A600 NTSC system in Canada (no psu, mouse, anything else other than the system itself), which may and probably will end with no bids. They say it's working, so take a shot and bid. You won't find anything much cheaper, and this way you get an extra floppy, case, and a working NTSC motherboard. Maybe you won't even need to take it apart, as from the pics it looks clean enough. :-)
