Matt,
Depending on how much you want to spend for a 50% fast-build kit, it could be in the low thousands of hours, or in the high thousands of hours. That's if you've built a kit plane before.
I would never discourage anyone from doing it, though, but the time and dollar commitment is gigantic (compared to Porsches). The ES uses a Lycoming IO-540 which will run you about thirty grand and the prop's another eight or ten. The Legacy (a two-seater) uses an IO-360 (same motor as a Mooney or Piper Arrow) and will cost 20k/8K. By the time you add avionics and all the goodies you've got some significant dollars into the airplane, and probably about five years of building time if it's your first one and not your only job.
Now, for the first-time kitbuilder, there are tons of lower-priced, much faster to build kits out there. Wag-aero makes a couple, like the ol' Wag-a-bond. . .
http://www.wagaero.com/
They also make some nice updated cubs, including a clipwing version for aerobatics. Easy to build, you can learn all the basic fabrication techniques, and once you had a couple of completed aircraft behind you, then step up for the Columbia 400!
And if you want to fly water, how about the Searey? A friend of mine built one, took him about a year, but he learned about rag and tube construction, covered the wings himself, mounted the Rotax, rigged everything and test flew it himself! Fun stuff.