It would help to post a photo. Understand that each "bottom" is composed of four "wear parts": plow shares, shins, moldboards, and landsides. The first two are the leading cutting edge and need replacement most often. The latter two only need replacement in really old, heavily worn plows. To replace the shares and shins would cost about $40 per bottom, whereas the moldboards and landsides could easily be $150 per bottom. This is assuming these parts can be found. The small rolling "wheel" is a rolling landside and if trashed, will be hard to find and expensive.
So whether the plow is worth that price depends on it's condition. If simple shares and shins would get it going, maybe it's worth the price. If the moldboards are shot, no way would I buy it.
These statements are true for most plows. I am not familiar with the Ferguson and don't know if parts are available. Personally if I needed a plow, I would look for a good Ford plow. You can get good ones ready to go for under $500 easily.
Are the bottoms on this plow designed to "trip" when an obstruction is struck? It would either have shear pins or a spring mechanism. If it is a fixed frame, non tripping design, you could not give it to me. I just blew $400 on an old Ford plow without trip protection when I bent the frame.
Post some photos if you can.