Question about webcams

Hi Guys,
Can anybody explain to me, in words of less than 5 syllables, why it is that an iSight camera is so much more expensive that a standard webcam?
I have just bought a new Mac Mini and I fancy the idea of a webcam for Skype and also so that I can put vocal videos on Youtube to scare the local cats away. Looking on eBay I find that a webcam in the Apple section will cost upwards of £60 and yet a webcam with some quality to it in the Windows >> Webcam section can be had for under £10.
I have compared the specs of both camera types and they seem very similar. 30 FPS at 640 x 480, microphone etc. I notice that the iSight camera claims to have much better light gathering ability than normal but you can't be sure of that until you compare both cameras in the lighting conditions they would be used in but by then it's to late 'cos you have already bought it.

So why are they so expensive and, more importantly, are they worth the extra money based solely on the image quality?

Cheers,
Steve

In one word of two syllables - Apple. There to make money, not friends.

Do extensive homework on other brands, and above all, read the reviews. There are several alternatives that work well with Macs. Because the iSight is native to Apple products and OS, it's likely to rank among the top contenders - at a price!

Thanks for that.
I'll get my reading glasses out and do some Googling.
Cheers,
Steve