My rims were made by Accuride, there were part numbers stamped on the rim. I contacted Accuride and was informed that my particular rim was discontinued but they gave me an alternate number for a close match plus recommendations on where to buy. Ended up buying one from a place in Florida. I have 295/80/22.5 size tires, my rim in 2009 was ~$265 including shipping.
You might try a couple salvage yards, try Visione Auto Mart in KY, they have a pretty big inventory of used RV parts.
2002 Monaco Windsor 38 PKD Cummins ISC 250 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi