It's true that the stuff they sell at box stores is dreadful, and at great expense.

Try and find a plywood dealer. You'll have better selection of products. At my local plywood dealer ifetime warranted sheathing luan 1/8x4x8 runs $12 a sheet and 1/8x5x5 non-certified baltic birch is $12. The 1/8" luan is nothing like the stuff they sell at box stores. There are no voids, but it's as ugly as rotary-cut marine ply. I've used VC luan in other thicknesses and would have no problem using it for a kayak skin. I plan doing it soon- I'll keep you posted!

m