Don't use the domain buying service - I wanted to buy a domain that someone else owned, so I sucked it up and paid GoDaddy $60 to negotiate a purchase. Firstly, using the domain buying service is really tricky. They send you to some other website where you have to get a new log in (can't use your normal GoDaddy one), and it's impossible to navigate. GoDaddy also tried to sell you like 100 other products in the process.
So I finally get the process going - GoDaddy then "appraises" the domain you're trying to buy (it seems arbitrary, but they say it's based on the length, popularity, etc.) and then you decide how much you want to offer and then GoDaddy is supposed to contact the website owner and negotiate the purchase.
I took GoDaddy's advice and had them offer the website owner the appraisal amount. But then GoDaddy spent and entire month trying to contact the website owner and NOTHING. No response. $60 completely wasted.
The worst part is, I decided I would try to email the website owner myself. Sure enough the guy gets right back to me and said he thought the GoDaddy offer was just SPAM. So I would advise anyone considering the GoDaddy domain buying service to avoid using it. And if you must, it's probably worth trying to contact the website yourself before wasting your money with GoDaddy.