Hi,
I use wired IEMs (at the moment, cheap skull candy titans with pro guard self moulded ear impressions) which work really well.
I use the stereo utility out from the desk, send that to a 4channel Behringer headphone amp and then feed that output back to a TC helcicon combined guitar and headphone lead.
I drop the headphone cable down the back of my clothes and plug into the combination lead. Job done, cheap as chips and the best monitoring I have ever had. The only downside is that the feed is the FOH mix so we have to be really careful setting that up at gigs.
At rehearsals, where we don't use any PA speakers the sound is stellar.
We have an electric drum kit and I've managed to persuade everyone except the singer and bass player to go 'in ears'. Even the singer uses cans during rehearsals.
Works for us and does not cost a fortune. Just be carefully setting levels and don't turn up!
Good luck!
Pre-Amp