Hopefully that is mostly surface rust on the table, spindle and column, but I'd sure try to low-ball because of it
, it does take some effort to clean up.
If you can see it and give it a quick once over.....
-check the table feeds turn and move the table(both x and y); of course they could be rusted too, but it does look like some dark and shiny oil spots on the dovetail ways....
-check that the motor, middle pulley shaft and spindle actually turn
-check the spindle for up/down movement
-if the table moves easy and there is power test the power feeds
Note that a full set of good condition tooling can cost as much as the machine!
Look at the vise, collets, cutters, chuck, a clamp-down set would be useful.
Then it comes down to the value to you. What capabilities does it add to your shop? How much clean-up/repair is required? Are used machines few and far between in your area?
I bet more than a few people here have similar/identical machines, so some support should be available.
It is also likely that a manual is available.
Oh, and be sure to get any special bits like the wrench for the collet nut.
With everything shown above and assuming it's all working, I'd be in the $300 area. But then machines can be hard to find up here.
Good Luck and let us know!
-brino