Barring any major defects in the cue, the most important thing for playability is the tip. The importance decreases the further you get from the tip; i.e., the shaft is more important than the butt.
You've said you don't want a sneaky pete and that you're concerned about ebay. Considering that, I would order something new from one of the big online retailers, like BilliardWarehouse, Seyberts, or Ozone. They will all stand behind their products. For the price you can't do better than the Schmelkes that Measureman recommended. I'd also consider Viking, McDermott, and Fury.
Personally I would stay away from the new Dufferins. The old house cues were made in Canada and played great; the new ones are churned out in China and don't play as well.
At the $100 price range your options are going to be hit or miss. Whatever you get, spring for a high-quality layered tip and make sure you get a common joint pin so you can swap out the shaft in the future. Among the Schmelke joint options, I'd go with #4 (3/8x10). That's the most common of their joints.