I have a big bag of grit that was pretty cheap at the farm supply store in Auburn... much cheaper than fish tank rocks from Walmart would be. I think it was called cherry stone - but I'm not positive, and it is too dark to go look.
The del's in port orchard does have large bags of grit in chick size and does not even have hen size grit. Please share bag size and price when light enough to see I may just need to drive some were else a Wilco just opened in gig harbor would they have it .