One of his domains is tomsdog.com. I don't know how much he paid for it, but I can get donsdog.com for about $10 a year. The list kaismh posted has 75 items in it, so say $750 a year.

The way I like to think about this is that if his after-tax income is $50,000, he is spending 1.5% of his income on domain names.