I'd also check out the whois info and see how long it has been registered. Assuming it is a .com address multiply the number of years by $10 to get an idea of

I'd also check out the whois info and see how long it has been registered. Assuming it is a .com address multiply the number of years by $10 to get an idea of how much they have been paying to keep it registered. They are going to want to at least recoup their cost in a sale (sunk cost fallacy?) so I'd offer them at least that plus 10% so they aren't insulted.