I am starting to build a Van's RV-10 4 place airplane.  http://www.vansaircraft.com .

 

It is a 200mph 4 place aircraft that takes between 1200 and 2000+ hours to complete according to Vans.  From looking at other builder sites and talking to other builders, the structure and required systems takes 1200-2000 hrs, but then add paint, interior, and other options that builders commonly add and you are talking 2600-3200 hrs to really get it done.

 

The advantages of building an aircraft is that you are then both capable, and authorized to do all your own maintanance.  This greatly decreases the cost of ownership.  The cost to build the plane should end up being around $130,000 to $150,000, but the closest certified aircraft to it costs $250,000 - $350,000.