Renting a softener from a Culligan dealer runs about $20 to $60 a month, plus any installation fee. Buying one pays for itself in about 3 to 12 years, depending on the rent and who installs it. Here are the rental prices dealers post and renters report, what the rent covers (salt is extra), what it costs to buy out a rented softener, what owning a 48,000 grain Fleck 5600SXT costs, the break-even at each real rent, and when renting is the better choice.