It looks more like a 56 than a 58.
Anyway it is a desirable smaller size these days, and a very attractive looking bike.
The mid 70's Super Mirage was a relatively nice bike - High Ten frame, but it had Alloy wheels, a nice cotterless crank and Suntour VGT-Luxe DR's - (One of the very best-functioning DR's ever made).
It is hard to judge the condition from the pic, but if it is clean, and you lose the dork disk/turkey wings and do the essential service, it would be easily worth $150-170.
It would bring even more if you install some DT shifters or Barcons, because people tend to associate stem shifters with dept store bikes.