Check out this thread on head-fi--the IEMs are sorted by price point so it's a great starting point for research:
Multi-IEM Review - 208 IEMs compared (Clear Tune Monitors CTM-200 added 12/10/11)
Personally, I recommend the MEElectronics M6. Amazing for the price and super comfy. If I hadn't wrecked mine during some field work, they would still be my daily portable set.