In order to give you a cost on a mobile home that is 30 years old we would need a lot more information to be able to even come close to an estimate. It all depends on the condition, how many bedrooms, how many bathrooms, the square footage. Also depending on if the mobile home is a double wide or a single. A quick check on the internet and I can find 12x60 with 2 bedroom and 1 bath are selling for $18,000. Another I found was a 12x63 with 2 bedroom and 1.5 bath selling for $21,000. It would be best to compare in your area or hire a real estate professional to help you price your property.