First off,

to GTTalk,
Second worth has so many factors. One of the biggest is verification of what it fits. Being that it's a 2 stage, looks to be in decent shape, based on value here (NW PA), $200-300 if you find what it fits and a willing buyer.
If you can't determine it's application, value drops by half in some cases. Buyers don't want to think or make major mods going into winter, they just want a blower.