I think the shareware model is not ideal, but the best of the worst case scenarios. Try before you buy didn't stop Doom or Quake becoming the mega-hits that they became and Id is where it is today because it started from those humble beginnings.

Anyway you cut it, someone will probably want to get something for free.
At least give them a trial version and then get them to pay for the full version once their appetites are wetted. Just like pushing drugs, only crunchy.