Comparable Domain Names	Registered	Sold for
loan.org	1997	$105,500
loans.com	1994	$3,000,000
rent.co.uk	1996	$104,000
rvrental.com.com	1996	$325,000

These prices and dates came from a variety of sources. You can see them here, here, here, here, here and here.
Like many web sites, this one logs visits.