Here's how I did it with my Nishiki Sport XRS, similar to your bike.
Drop bar with brake levers- $20 (swap meet)
Bar Tape- $7 (closeout at LBS)
7sp Bar end shifters- $30 (friction shifters- Suntour Barcons- swap meet)
Brake levers- (came with bars)
misc cable/housing- $10- $20
I also bought a stem adapter and stem, I think about $25 total for both.
From this
to this