You really seem to want that SX10IS. Each generation gets better and the SX10IS is two generations old. Spend the extra $50 and get the S4000 or spend a little more and get a Panasonic FZ40.
The SX10 IS is a good camera. My sister-in-law has one and I've seen her pictures, but I can't see getting an older used camera when you can get the newest technology in a similar level camera for $50-100 more.