Cost? What cost? The Mods are free and most probably the people doing the actual hands-on website updating and hardware maintenance are either volunteers/friends of his or they are low paid, part-time employees.
I'm not even sure if this site runs on it's own hardware anymore or is run on a Webhosting Company's hardware. I remember a few articles on "The Anandtech Server Farm" but that was awhile back.
No doubt that bandwidth is not cheap. But the ads alone waaaay more than pay for the bandwidth.
What is Anandtech.com today surely started as a labor of love many years ago, out of his own (parents?) pockets. No doubt about that. It has become a successful business through a lot of smarts and hard work. When Anand or an employee flies out to California for the latest NVidia conference and stays in a hotel, those are business expenses and deductible. If they pay for it vs. being taken care of by the company.
So yeah, now he's making bucks. 10 years ago, not so much.