Again, thanks to everyone for their advice on this issue... after I calmed down from the initial shock of possibly purchasing a p.o.s. I think I have come to my senses. I finally got good weather and got the bike on the road. There are some problems with shifting but it only seems to occur while shifting to a "higher" (read harder) gear ratio. Is that normal for a detent to only wear out to cause shifting in one direction harder than another?
In reply to gmcastil, one LBS gave me that option of a quick shot with the WD-40 but at the same time was showing me the newest 10 speed component set... I decided to go to another bike shop to get their opinion and I was surprised.
First, they told me never EVER spray WD-40 into any STI style shifter because of its caustic nature on the plastic components. This came to a surprise to me. Secondly, it appears that very few people actually know how an STI lever works. I cannot find a shimano schematic anywhere. A quick trip to the library or book store will show that bike repair manuals recommend completely replacing STI shifters before attempting to repair them?! As an engineering student, this presents a problem; on one hand I really really want to take it apart to see how the thing works, but on the other, I don't want to pay to replace it since I am a poor student... meh. So the consensus is to not buy STI shifters off of eBay even to have as backups??
In response to cmg and bikinfoolferlife, I have cleaned the cables and housings as well as I can and there is good tension between the messed up shifter and the rear derailleur. The rear derailleur is a little dirty and will be fully cleaned the next chance I get. As for the cost of the bike... $250 with a car rack included. I didn't think it was that bad of a deal considering the bike was literally sitting in a garage (spelling) for the last couple of years. The frame is immaculate and there is only one chip in the paint thus far. Before I bought the bike the original owner confessed to not understanding the controls of the bike which may have led to their abuse, but again since this bike will be mainly used as a commuter and for weekend trips, it will suffice. Even with its current "problems" it beats my 50 lbs of old school roadmaster touring bike with balloon tires, more rust than paint, down tube shifters and more squeaks and rattles than a sane person can stand. Again, thanks for all of the feedback.