buying domain names

If i wanted to buy a domain name that already exists, how would I go about doing that on making the offer?...how do you know what a domain name is worth?

is there a web site that has a list of domain names for sale and their prices?

- nate

Like all things, they're worth what the purchaser is willing to pay for them. The company I work for has been aquiring a lot of alternate spellings of our domain name and they can cost anything from £50 to £3000 (though we got an EU TM with that one too)