Best budget camcorder for mainly audio.

and where you place the mic(s).

All camcorders (and cameras that can capture/store video) have an automatic audio gain "feature". For "normal" audio levels, this works fine for most folks. Also, if there is a lot of space between the mic and the around source, keep in mind that all that "space" will contribute to what the mics can hear and ultimately what gets recorded to the camcorder/camera. Most low end cameras have no audio gain control.

If the audio is really loud, it is likely that the auto mic gain will be overwhelmed and the recorded audio will sound very muddy or perhaps even have a lot of static ("peaking"). This cannot be fixed after it is recorded.

In this case you should probably find a camcorder with some sort of manual audio control. There are two basic methods. First, there is a "limiting switch". Generally, this method has a menu selection for normal or high audio levels. For the few Sony camcorders that have this, look for "MicRefLevel"; for the few Canons, look for Mic Attenuation". I did not check the Zi8 or Q3, but the FS200 does not have the control (just check the camera's manual).

Even better would be more granular manual audio, but you won't find this in camcorder less than about $700, so that won't be covered here.

Another method is to get whatever camcorder you want, but also get a "field recorder" to record the audio. I like the Zoom H2 and H4, but there are lots of good ones out there from manufacturers like M-Audio, Tascam, Edirol, Sony... and a bunch of others. They all have manual audio control (on top of auto gain). The short version is that when you edit the video captured by the camcorder, import the audio from the field recorder, synch with the video, mute the audio captured by the camcorder... While this is an extra step to do the synch, an advantage to using this method allows the "spatial" properties of the audio to remain in one place (don't move it once the field recorder is placed, then it does not matter where the camcorder video is captured from - remember, if the camcorder moves, so do the built-in mics so the audio characteristics will change).