Luckily the guy at costco will let me do two transactions to get two 15 pill packs to last for a while.
Most states have a reasonable limit, like 3.6g/day purchase (up to 7.5g/month). At 60mg per pill, that's 60 pills in a single purchase. It sounds like your Costco guy doesn't know what he's doing. With the log book, it doesn't even make a difference that you split them into two transactions, the limit is per day not per transaction.