That sentry might be the best thing I've seen in a long time ^^
On topic, there are a few low-tech solutions today. I'd assume what you're worried about is the queen, which should also have the highest value to a potential buyer.
You can simply mark them, for example with DNA or microdots, of which there are many bio-safe variants for use on pets (or bees).
We had a queen-hive when I was younger, and we marked them with felt-tips to keep track of numbers, worked great ^^
As for trackers; they'd be impractically large to work properly for the bee,or too small to function at all at range...