Remember that earnings is income minus expenses. So this includes the cost of maintaining the site. If it is a full time job then the buyer would be purchasing a 50K job.

Also generally smaller companies go for lesser multiples than larger companies. It really depends on how much time and attention the owner has to put into it. In the case of a publicly traded company that is close to zero for shareholders (unless you own Yahoo). But for a small business you'll have to keep an eye on things even if you do hire a general manager.