Yes, bergamots aren’t something one runs across everyday in the supermarket, or even at greengrocers. But mid-winter, depending on where you live, you just might get lucky and happen across some, as I recently did. Twice! (Although the second time took a bit of moxie.)
There’s conflicting information what a bergamot actually is, but it’s definitely a member of the citrus family and most consider it to be a relative of the bitter orange, which might have been mated with a lemon at some point in its dubious past.