I am checking into this for my family as well. I spoke with the Rainsoft lady today and she said they recommend replacing the bulbs every 2 years. Is your distributor telling you they need to be replaced already?
The Rainsoft of Indianapolis company will sell 2 bulbs for $105.93 and will ship them...you have to put them in yourself. I thought this was really high..if I find anything better, I'll let you know!