yeah - adding a Mic input really limits your choice of consumer video cameras. most don't have one...
If your output requirements are youtube, you could get a digital video cam like a FlipVideo, and also get a digital audio recorder down the track like a Zoom H2 and use editing software to sync the high quality audio with the video. (use a clapper board, it will make you feel good too).
If you want to do DVDs then you want to think about getting something like this (out of your price bracket);
Sony HDR-HC7 good picture with ok mic input.
http://www.amazon.com/Sony-HDR-HC7-Definition-Camcorder-Optical/dp/B000M3HVLQor something with 3CCDs.
If you aspire to do nice cinematic stuff, you might like to look at some of the new Nikon DSLRs which do really beautiful cinematic style video in HD (again, out of your price bracket).
New Ipod Nano is a cheap short video option - I've used one a bit and the picture is..not too bad.
Have fun!