I think that's a bit much for used... but... it may be a good idea to shop around first for that same model. 100 brand new after shipping sounds about right, but might want to check your local feed store first to see what they have on hand.
If you are going to spend at least $100 you should look at GQF manufacturing and their Hovabators. The 1588 is one of the best you can get as a home hobby incubator for about $115. The thermostat comes preset and you shouldn't need to tinker around with it. The turner is available for additonal cost but well worth it. I have 3 and love them!