The budget conscious way of recording the audio to a high standard is to use a clip-on lapel mic plugged into a Zoom H1 that you conceal by putting it in your pocket.
As covered previously, the problem with most camcorder microphones is that they are designed to record everything in front of the camera, which includes background noise and traffic. By clipping a lapel mic to the sound source (you), you close the distance and eliminate much of the unwanted background noise.
This way you can move freely without the aid of a wireless microphone setup and you can synchronise the audio to the visual later. This is easy to do, you simply snap your fingers or clap in front of the camera when both the camera and audio are recording. This creates an easily recognisable point that will help you sync the audio / video later in the edit session. If you are creating multiple scenes you may wish to invest in a clapperboard so that you can write the name of the scene / take on it and clap it at the beginning of the recording. This way you can easily identify and name the clips later.
If you are recording the footage and adding your voice later, a clapperboard will be essential to identify which audio file goes with which video file. By simply assigning ‘scenes’ and ‘take numbers’ to your recordings this becomes relatively straightforward.
Oh, it is also worth mentioning that mobile phones should be turned off if in close proximity of the recorder. Even if they are on silent they can interfere and ruin the recording.