I certainly wouldn't put the expensive bracelets out there in front for EVERYone to try on, but, even though baggies are a little tacky, it's your best idea of the three you presented. People who seem genuinely interested should certainly be, not only allowed, but encouraged, to try them on. They shouldn't have to ask - YOU should suggest it. (You might make the sale)!
No Touching signs can seem very unfriendly. All the best of luck at your show!