I think Fir is a good bet. Seems like 2x6s would be wide enough.
Like Chip said, pick good wood. Find something with a tight and straight grain pattern.
Then draw or trace your pattern and go to town.
Id add a drawknife to your tool list to remove wood fast and then use a hand plane to finish the shaft and blade. Feel free to hit me up with any question; [email protected]
Thanks for the plug Randaddy, my oars arent that expensive though.