I usually buy them at Stowaway if I'm in the area. There's a minnow shop on 1097 near April Sound (if you don't get them there). The place is Lake Conroe Bait Shop (936-231-0409) and there is that gas station on FM 830 as well.
"Follow me and I will make thee a fisher of men!" Bust open my nets LORD!!! because, I am a wishing I was a fishing!!