I'm pretty sure the Gran Sport was only made in the period 1980-1982ish. The serial number stamped on the side of the seat tube, near where it meets the bottom bracket, should tell you the date - the first two numbers are the year.
Now, to get to your question, yes, if the bike was in next-to-mint condition, I would pay that for it. Many people would find this crazy, but I have a soft spot for Apollos, and the Gran Sport, with full Shimano 600 Arabesque group, is a damn nice bicycle...especially if it's a burgundy one...I have only seen them in black and burgundy, and while the black is nice, the burgundy is fantastic...