Originally, the floor monitor was used solely for vocals, and everyone brought their own guitar amp. The room dynamics are part of the issue here - the 45 degree half walls on two sides, the low ceiling (8 ft.) just make everything bounce right back to the center of the room.
The other part of the problem came when junior got good (and very loud) on the drums. He couldn't hear vocals or guitars, so I used an old 180W bass amp to use as a monitor strictly for the drummer to hear vox/guitars. My bass rig is right next to him (and oriented towards him), so he gets about 600W of bass aimed right at his coconut - he feels that fine enough.
This is our only drum kit (and has subsequently cost me a small fortune in cymbals), and he uses it for practice and gigs. Getting a smaller one for practice is not going to happen. Besides, he's 13 and wants to rock to Sabbath and The Who, not play any of this synthesized pansy music that most of the kids are listening to these days. For this, I am thankful and look for another solution other than turning him down.
If IEM's are the wrong tree to bark up, then that's fine - I'm just curious. As for price range, I was hoping to get both kids outfitted for <$800. Not sure if that's possible or not.
The plexiglass is interesting...I will look into that a bit.
It must sound weird to most, but I'd sell a nut to keep these guys (and their friends) upstairs and playing instruments rather than driving around looking for stuff to do - sometimes, Jam Room overkill is a lure.