FWIW, here where boating is a warm-weather activity for most, Wal-Mart clears out the orange Fox40 Micros (with an IMO lousy lanyard) for $2 at the end of the season. Maybe in your area too...check next fall!

For carry on a keychain, I found I had to reinforce the ring hole with epoxy glue to make them last. The Micros aren't as loud as the regular Fox40s, but way nicer to EDC. They also make a kiddie's version of the Micro that's easier to blow.