I have a 1941 model C, clapped out from being in production from ww2 and I suspect that the spindle may be bent ever so slightly. I paid around 375 to 400$ for it in the North East.
On the flip side, a friend from the Golden Gate Live Steamers just sold us a Sharp 9x42 bridgeport clone with variable speed head for 1000$ out in California.
When your dealing with used machinery, there are just way too many variables to say for sure. These tools are worth what some one is willing to pay for them, simple as that.
A Southbend 9" lathe is a very nice lathe for a home workshop in the 9" size range. However with that said, a HF 8x12 or Lathemaster 8x14 is a new option that replicates a C model, and I can say this from experience as I also have a Lathemaster 8x14.
When you are talking 1500 to 3000$ for a lathe, there are just so many better options out there than a 9" Southbend, used and new! 12x36 lathe is certainly one that should be seriously considered!