Putting out stakebeds

I'm in the process of starting to gather approx. 8 ft. long wooden strips to use as stake beds in deep water and am having a hard time finding the wood I need. There are none that I can find for free. I have checked lumber yards, saw mills etc. near me. I know hardwoods would be best, but I'm unable to find any that are available near me and that I can afford. I have a lead on some spruce and what is called whitewood I'm just not sure how long the will last under water. Any ideas?