Buying and installing a customer-owned aboveground propane tank runs about $450-$1,000 for a 120- or 250-gallon tank and $800-$2,500 for a 500-gallon aboveground tank. Installing an underground tank can cost around $1,800-$3,000 for 500 gallons and $2,000-$3,500 or more for 1,000 gallons.read more >>