Oh what a beauty!!
That model pictured is identical to the US models for 1979-80. The US 1981 models had white trim instead of rust. I don't remember what the US model cost for 1981, but I do remember the 1976 model that I have sold new for about $240 in the catalog, $250 in the stores.
These machines were pricey, especially since they mostly plastic, and Sears vacuums weren't known for being very long lived. I remember buying bags at Sears in the 80's for an early 70's machine, and the sales lady couldn't believe a 10+ year old machine was still running.
I do know that about the same time(1981) you could buy a TOL Hoover Celebrity QS with Quadreflex p/n for about $225.
These Kenmores are fun, and IMHO very collectible machines today.