Yes they are very variable in quality and price...
The webcam I have isn't sold anymore, and I wouldn't recommend it either, as it was a pig to get set up with drivers etc..
I've just had a quick look around and found
this one at ebuyer.com which has some good reviews.
As for headsets, I'd probably be tempted to get something like
this one - the reason for going for a USB headset over a normal one is that you don't have to faff about with unplugging your speakers if you don't have front audio connectors on your PC.
If you do have front panel audio connectors in the PC and they work (try plugging your existing speakers in the front and see if you get anything), then you could go for a cheaper headset if desired. Ebuyer have loads of headsets -
direct link to headset categoryNot endorsing Ebuyer by the way, just they happen to normally have a massive range of peripherals to choose from, usually at decent prices
Just to re-iterate, I haven't got any of the products that I've pointed out today, as I don't use internet audio chat at all, so have no need for a headset, and I already explained about my webcam!
Hope that helps