Here’s a good resource if you are in the market for used poles, especially wood poles. We put together usedpoles.com as a free resource for buyers and sellers to trade used poles, and maybe other building materials, too.
I always feel compelled to mention that I don’t necessarily recommend using used poles for your project. Some poles were removed for a reason so think hard about your intention with your building project. If you are building something that is structural, reconsider using used poles to save money. You might be much better off in the long-run by installing new poles. If you are building something that is purely aesthetic, then go to town with yourself and your used poles.
Just make sure you know what you are buying.
That said, here is usedpoles.com.