There's cheap and there's inexpensive. I find that buying the cheapest
thing has a high probability of wasting your nominal investment. I
bought one of these relatively inexpensive webcams for about the $24
it's going for now:
http://www.newegg.com/Product/Product.aspx?Item=N82E16826104354
...and have been happy with it. Unfortunately, I cannot accurately
measure the cable at this moment, but the specs say it has a 5' USB
cord. At any rate, you can buy extensions for a few bucks at monoprice..