I have a Venture 17
and love it! I paid all of $400 for mine, with trailer, and other than the trolling motor, I've put in maybe $150 into it. I might repaint it at somepoint, or I might not! The boat sails well, and is easy to rig/launch/recover. I think they're cheap because:
1. they're older boats
2. Some of the stigma of the Mac 26x slops over to the older Mac's.
The original owner of my boat was a member of the Battery Park Marina, if the window sticker is to be believed!