I've started visiting my local university library for a few hours to get work done (I'm not a student).
The WiFi is fast and reliable, the environment is peaceful and conducive to heads-down work, and the parking meter costs around what I'd pay for coffee.
My latest low-cost co-working spots are the public library and hotel lobbies.
The library unfortunately is only open 2-6p on Sunday. Big chain hotels have huge lobbies, seating areas, and free wifi. They are usually busy in the mornings with everyone checking out and so they have never bothered me.
