I just posted a new ad on Airstream Classifieds.
This pristine OEM WFCO WF5110H Inverter was just removed from my 2013 International Signature 30' when I had solar installed by AM Solar. Works fine. You will need the remote switch, which runs about $50. Buyer to pay shipping cost, prefer local pickup or will consider meeting up if our paths cross.
You can contact us by filling in the form on the right hand column of the ad listing: