According to the headbadge that bike was built on the 257th day of 1979, otherwise known as September 14, 1979, making it a '79 Le Tour IV:



In 1979 Schwinn set up a "torch brazing" operation at its Chicago plant as part of a last ditch modernization effort and built Le Tour models there for '79 and '80 only. Unfortunately those frames were made from 1020 steel, that bike weighs 30lbs in original trim. The same frame/fork was used on the more expensive Super Le Tour II, but that bike had upgraded components including a Shimano freehub with a 6-speed cassette (both firsts for Schwinn).

I don't think it would be worth much more than $150. A '79 Super Le Tour II might be worth a little more to a Schwinn collector because it was the first 6-speed/cassette Schwinn, with early Shimano Uniglide.