Sitka Spruce comes from the "Sitka" area of Alaska. The trees grow slow and the growth rings are very tight. It's almost un-obtainable. Only speciality wood outlets "might" have it or speciality "boat wood outlets". Also very expensive. Totally different animal from the spruce 2 x 4's. It's so valuable that the Guitar manufacturers by it years in advance of cutting for tops. Aircraft hobbyiests also use it.

You can use tight grained fir and some regular spruce for paddles. (actually you can use just about anything) But you want a stiff strong wood for the shaft. Closet poles make good shafts and are clear and tight grained and redialy available.

If you're doing a composite paddle, you can use spruce or fir and laminate a hardwood piece down the middle etc.

Call around for the Okume. Some people build S & G's wih 1/8 luan $8 for a 4 x 8. Not bad. Beginners get frightned by this but there's plenty of boats made with it.

Good Luck