Matt,

I use big box store lumber (home depot or lowes). I pick thru an entire rick of lumber to get one or two pieces, usually.
So I go back mutiple times to accumulate lumber for a kayak.
Usually I get about 40% in strips.
So a 16' kayak needs about 4 each 8'x4x4's @ #15.84 = $63 with some left over.
I use a little walnut and poplar or maple. $10 with lots of stock left over.

If you go buy clear cedar I'm sure it is much more expensive, but here in Texas I have to order it special and don't get to pick out the good boards.

Wish I had a local supply that I could spend more for clear I could choose from!