Hi Alan, the Scott Bonnar Model 45 was first introduced in 1968 and came in 3 cutting widths; 14", 17" and the 20" (which also sported an 8 blade cylinder reel).
These machines all had a solid engine deck; the 14" powered by a 2.5HP Briggs and Stratton, the 17" had the HK25 2.5HP Kirby-Tecumseh (later the HK30 3 HP) and the 20" always had the HK30 Kirby-Tecumseh engine fitted.
Your machine has the twin rail engine deck and the Kirby-Tecumseh engine and was produced roughly between 1973-74.
As for the price, these machines were always expensive, the cheapest Scotty, the Bonmow, was 75 pounds 15 shillings and sixpence in 1957, which was a lot of money back then. The last Rover 45 sold was almost $1900 a few years ago.
