This Ebay source has many RV parts from time to time. I keep their address on my frequent look at list.
Furnace, Water heaters, Access doors, sinks and you name it. Usually have an RV item most of the time. Appears to me that they must live close to an RV manufacture. I have purchased items from them before.
EBay name: member23443
http://search.ebay.com/_W0QQfgtpZ1QQfrppZ2...3aMEFSXQ3aMESOI