We came across some used for hi-fi units consisting of a transmitter a small belt pack with a 3.5 socket and a cheap pair of in-ear phones for £30! They plug into MON 1/ Mon 2 of the deck and you can send whatever mix you desire to it (be it just your instrument / voice channels or your desired mix of the full band)
Worth changing the in-ears for better quality (or in my case I use a mono earphone in one ear and leave the other free for the "real sound".
The other handy point for use they are tunable across the same channels as The BBC use for O/S Broadcasts which has been great when involved in bradcasts, interviews etc.
I look up the model number and see if they're still available (we've had them about 5 years.
never had any problems with unplugging noises since we switched to silent jacks!