Hi Michael, are you sure that is a Scott Bonnar? If it is, it should have a plate with a serial number that identifies the model, but I don't recognise it. It is obviously a rather serious mower. Can you post some more pictures please, showing more detail of the mechanical parts? I would like to see how much meat is left on the blades on the reel (how many times it can still be re-ground) - your picture is out of focus in that area. I would also like a low lateral shot of the inside of the chaincase so we can see what the condition of the sprockets is. A picture or two of the Honda engine might help us to guess what condition it is in.
Essentially, unless that mower were a rare and desirable model, I think $250 would be a fairly big ask on the east coast, but I'm conscious that reel mowers sell for much higher prices in Perth. To go into more detail, a new GX160 engine would be worth quite a bit more than is being asked for the mower, and the mower so far looks to be in relatively good condition. Furthermore whatever brand and model it is, that has been a top of the line mower, probably used for putting or bowling greens judging by the large number of blades on the reel. On the negative side, getting a grass box made for it will cost more than is being asked for the mower, even after you get detailed design information thus making it possible to manufacture one. Replacing the missing chaincase will be at least comparably expensive even if it is a simple one - if it had a cast aluminium chaincase it will be near enough to impossible.
Let's get more detailed information on the machine, and things will become clearer. Finding a source of genuine examples of the missing parts would make a big difference to the practicality of restoring the machine, and that requires identifying it.
