Gotcha.
For budget wireless systems, balancing cost and plausible performance is crucial. For wireless, the general consensus seems to be that the Shure PSM200 system is about as cheap as you can get away with. But I've known a couple people who were happy w/ the Carvin EM960.
For low-budget wired systems, the main contenders are the RockOn system, the Rolls PM 351, or a headphone amp.
The Tasty Blender provides a limiter, which is crucial to have somewhere in your system. Both the Tasty Blender and the Rolls give you the ability to tweak the mix from your mic position. That's not so important if you're using a WiFi controllable board, but it's otherwise handy. The downside, is that you'll be running a lot of wires to the mic position. That's an issue of stage aesthetics—especially if you use the mic-stand bracket with the Rolls 351. But more importantly, it means your band's stage or monitor mixer needs to be able to send your IEM satellite unit one aux mix for the Rolls or up to three mixes for the Tasty Blender. (How many unused aux sends does your system have?)
With these wired systems, the upside of having the IEM satellite at your mic stand is that you can combine the bass instrument cable and your IEM cable to keep the weight off your earpiece cable. (This assumes you're not using an instrument wireless.) Put a pedal tuner and your IEM satellite on a board by your mic, and a 15-ft combined cable will give you about a useable roaming range of ~20+ feet. (A 20' combined cable gives you an almost 35' range.)
If you rack these units w/ your stage rig, though, you'll be tethered a bit more tightly than you might like on any but the smallest stages.
That's one of the main problems IMO with using a headphone amp, unless you can keep it in a small and shallow rack by your mic position. The other issue with headphone amps is you need one with low noise and sufficient gain. (The better the seal on your earpieces, the less gain you'll need.) OTOH, a headphone amp can be the ticket if you play mostly tight stages. Then, a unit that allows you to mix one or two aux mixes with a different more-me channel for each headphone output can work for multiple members of the band. (In addition to you, the drummer and a keyboard player could all be wired from the same multi-mix unit. You might be able to get a guitarist on the same system, but not if he moves around a lot—highly mobile players will not only run off the tether, but they'll also cause lines to tangle.) If you want to get the rest of the band on wired IEMs w/ headphone amps, it'll be better if you have at least a couple headphone amp units just to keep the wiring distributed. But that's still a cheaper route than investing in PSM200s for everyone in the band.
