How about Soundman.de in-ear mics? From Germany. They're tiny and very detailed and about the same price as CA-11.
http://www.soundman.de/ If you can figure out the confusing website, or just email Soundman, they can tell you what the right mics are for you--they have various sensitivities. They respond quickly to email.
You probably do NOT need the most expensive ones, which are very precisely matched for studio recording.
I run Soundman-->battery box-->Line-in-->Sony PCM-M10 to record loud live music. For what it's worth, I've seen disappointed reviews about the Soundman battery module, which is only 6 volts. Since the mics can handle up to 10 volts, I use a 9V battery box with them that I already owned (SoundProfessionals).
But you're not recording loud music. You're recording quiet sounds, and if you're using a preamp, or a recorder with a good built-in mic preamp, you wouldn't need a battery module at all.