You found a pretty decent bike. From the down tube shifters it would appear to be from the mid-1980s, and I think it was made by Miyata. Without actually looking it over it is difficult to say how much work it actually needs. Tires, tubes, cables, brake pads would run you about $40 + S&H from Niagara Cycle Works @
http://www.niagaracycle.com/ Nashbar has a Selle saddle (Nino model) right now for $14.99 (MSRP of $35) if you need one. Is the paint in good shape? No rust and only minor scuffing or scratches? Simple Green or Fantastik spray cleaner, Turtle Wax Polishing Compound and/or Turtle Wax Rubbing Compound, and car wax can help bring the paint back up to code. If it is in great shape, since it wasn't used much, you could always dismantle it and wait until you find the right parts at the right price to finish it. From a "C&V" standpoint, this is a bike you would want to get back on the road and ride, since it is your size (23"/58CM frame) or sell at a decent price ($175+ depending on season & market) when fixed up. Hey, that's the way I see it. Either way, you made a really great find! It is also a good think that you saved an excellent bike from a land fill.