RVParkStore.com has 1 RVs for Sale in San Diego County, MT. Find the perfect RV, camper, or motorhome in San Diego County, MT. The current average listing price is around $19,900. RV prices in San Diego County, MT have remained unchanged at approximately 0% compared to the 12-month average price of $19,900. Listing prices currently range from about $19,900 to $19,900 depending on the size, age, and mileage of the vehicle.