I form them myself, which takes about 5 minutes on the Secretary of State's website. The only fee to the state is a one time formation fee. This is true in a variety of states.

I got this advice to do so from (a) the aforementioned nonprofit consultant and (b) an actual attorney, who does serve as a registered agent, for no fee. He is glad to do so since in the very rare event of a lawsuit, he'll be the one representing us. However, you could also just be your own registered agent if you have an office where people regularly work.

Note that I am not going out of my way to conceal the identity of the nonprofit board members / members of the LLC.