It's a good machine for that. Obviously, the question of what it's worth depends on whether it's in good shape, but careful inspection and testing should be able to settle that. Does it have any tooling with it? Does it come with the computer used to drive it, or would you have to provide that? If it doesn't have the computer, does it have the control box and cables? Is it under warranty, or as-is, where is? Can you visit it and see it run?
There's a thread that's active today (Need Help!- Sherline mill for cnc or maybe X2? - need opinions.) where people are debating the relative merits of a machine like this versus a Chinese retrofit. Advocates of the X2 point out that it can take a heavier cut, but Sherline partisans respond that this is not the most crucial thing for a small mill to do. For most projects, it's more important to be able to spin a small tool faster than slower but with more torque. These Chinese machines generally drive the spindle with a plastic gear-train that isn't exactly the ultimate in quietness, longevity or efficiency. Their workmanship varies from acceptable to not. And their coarser, looser leadscrew assemblies are not optimal for CNC conversion. But they are cheaper and heavier than the Sherline, if that matters to you.
If what you really want is a Bridgeport, save up for one - the Sherline doesn't do what it can in terms of heaviness of cut. On the other hand, the Sherline, with its faster spindle, will do a better job on small details than a Bridgeport can, and that's what small models usually require.