@Jan, I'm going to price out pharmacy loperamide with Costco. I buy a few medications and ask them not to bill insurance purposely because paying cash for a 12 month supply can be cheaper than using insurance/copays over months. It might be relatively cheap.
@CTB, yea you can buy more on separate visits. The limit seems to be based on the transaction so more transactions (more shopping days) shouldn't be a problem. My wife has been picking me up a box 1x per week at Costco so I can stock back up.