nor have I, tho I havent really looked yet either. this week Im heading to a electrical supply store for some not so common resistors so Im gonna see if they have the relays there. I only know they exist, but dont know where or how much. for time being the manual switch will get things done atleast; my inverter is tucked into the glove box next to the PC, so its a real PITA to flip.

 

well you can do a short time delayed relay yourself. The basic is just a simple relay and a Capacitor (size depends on the relay and time). Wire it up so that as long as power is on, the capacitor is charging and the relay is on (feeding power) When the car is off, the capacitor stops charging and discharge keeping the relay on. When capacitor fully discharge, relay clicks off and inverter is turned off. A simple 12-14V relay to replace the inverter switch and wire the capacitor (also add a diode to prevent discharging back into the battery) parallel with the relay.
You would have to tap into the cig lighter for the 12V to turn the relay on and charge the capacitor.

 

not a bad idea you got there, would be a bit tricky to come up with the proper capacitor to keep it running for preferably about 1minute. hopefully it wont take anything too large.

thanks for the idea tho, is this what you used on your system?