Res Care (same as Res Up) is available delivered to the door for $16 per gallon. The recommended maintenance use of Res Care is 1-2 oz per cubic foot so for a 2 cubic foot softener the cost per treatment is 25 - 50 cents.
I get Pro Res Care by the gallon 5 minutes from home for $14 Canadian. The dispenser cost $22 with the softener. I dont think that it is very expensive as long as it works to keep the resin clean of iron etc.