What that is worth depends on who is looking at it. When I look at it, I see a well used anvil with some damage but it still has use in a forge. The edges, surface and table can be dressed and used as a teaching anvil, or when doing something like punching where I may damage my "good" anvil. The sway is bad for knife making but not too bad for general blacksmith work. With those eyes, I may give $200-275 to use it as a beater in my shop. The main reason is, I may hit that thing once and break it in half. It may last for decades in a shop but there is no way to tell which will occur so I prefer to spend $600 for a new anvil with a warranty.
All of that being said, I bet you, if you dress the edges, table and surface, someone will pay you $4 a pound for it.