Almost surely a scam. No reputable RV re-seller is making cold calls to buy used RVs, especially at retail prices. Dealers buy wholesale, whether at auctions or by taking trade-ins. They can't buy yours at retail prices and expect to make money on a resale.
Just tell him to wire the full asking price to your bank and you will transfer title once the funds have cleared. Ignore any schemes where he sends a check or has somebody else pick it up for delivery. He will probably stop calling . There are dozens of ways to scam this sort of thing, so don't get sucked into reasonable sounding but oddball arrangements.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL