I don't know how close you are to Reber Ranch in Kent (I'm in Covington), but they have the best prices ($1 less per 40lb bag) out of anywhere I called in the area. If I were you I'd just use up the medicated you have (I'm still getting through mine, and though I know a bit better now, the peace of mind of using medicated was better for my personality, LOL) and then make the switch if you think they'll make it through another bag of chick starter before needing grower.