Generally I buy my domains from GoDaddy for around $8 a year. Sometimes I'll buy a domain on expired auction for $18.95 But last month I paid $193 for an expired domain... and just now I paid $176 for a domain. I think the price was worth it because of the traffic the names receive. What's the most you've paid for a domain?
Do they earn anything? I park some on Sedo....and I get around 100 visitors in total per month, and nil revenue.... I believe just to earn a bit needs about 10,000 visitors per month, so your domain better be hot...and of course the price goes waaaaaaay up from $8 And its no use to blame the parking provider because only lots (and lots) of visitors can earn anything substantial.....
$70, back when Network Solutions was the only game in town. I've never purchased a domain from a private seller, but I've been tempted a time or two.