I've done this sort of thing in an amateur way on avi files using virtualdub and audacity - not perfect but not as tedious perhaps as your post suggests.

Clapperboard markers would help, but this is what I did:
(Recordings need to be digital to have a chance of timings matching and should have the same sampling rate.)

Make an avi of the section of video I'm dealing with.
Extract the audio from the avi using virtualdub.
Load the resulting wav file into audacity.
Load the good quality audio as a new stereo track into audacity alongside the camera audio.
Using the waveform graphics as a guide, position the good audio to match the camera audio - in audacity I can zoom in to help get it as close as possible. (How easy this is will depend somewhat on how good the camera audio is - the less extraneous noise the better.)
Silence the camera audio track(or edit it to mix in some ambient noise if desired).
Export the result. I now have an audio file to match the video.

Now I run virtualdub using the new audio file as the audio source (go to the audio menu to load it) rather than the audio from original video.

Make sure I've set my compression options (for video and audio), in virtualdub you can create processing settings files so I can effectively create my own presets.

Use the output play button and window to preview the result. Make sure I check at a point near the end as well as the beginning - sync issues can be incremental. If necessary, fine tune using the interleaving option in the audio menu. I found getting the mouth movements of vocalist looking right is the more important thing to use as a guide with this - you notice this more than you do other stuff.)
Now I save the new avi.

Without using expensive equipment, software and expertise I don't think you'll find an easy way to do it. This way is free and I'd imagine about as easy as it will get.