I'm looking for a switch to mount in an upstairs hallway that will control an attic/roof ventilation fan. The switch will select whether I want the attic thermostat to control the fan, vs manual-on, vs off (fan will not come on). The price for something like this (center-off, constant-contact (not momentary), single-pole double-throw aka "3-way") whether toggle-style or flat (Decora or similar) is upwards of $50 - $70. Or I can get a plate-mounted SPDT center-off paddle-style switch (something you'd expect to see in an airplane cockpit) for under $10.
I could swear I've seen these 3-way center-off switches in the past. Why so rare and expensive now?