a088008,
I ask myself that same question very frequently. I'm a big fan of scratch building, and kit building. I pretty much only fly things I've built, most of those are scratch built. Typically I'll only get an ARF if its something I really wanted that wasn't available as a kit. (Swiss Trainer from Hobby Lobby, or now I want the Graupner Monsun)
I'm such a fan of scratch building that I'm selling my designs as kits.
Oh, and speaking of scratchbuilding, I'm building two Canadair CL-415s modified to be 215, starting in January. I'm using the plans and fiberglass parts from
www.mraerodesign.com
--Paul