Greg,
The cost will vary a great deal, but still costly. I run there with the Greater Washington Section of the Mercedes Benz Club, and we can't do it alone, because I think two days for the club was something like $12,000 (I don't remember exactly, except that it was a lot of money!!) Consequently, we had other clubs join us - last year it was the BMW's, Audi's and and Porsche's clubs. We had to have at least so many people running for it to be cost effective. And the cost per day for individuals was a very reasonable $180, I think.
BTW, even booking a year ahead, we could NOT get a weekend date!! Even the NASCAR guys practice there.
VIR is a country club for motorsports, a really great facility! Keep tabs on the Mercedes Club web site at
http://www.gws-mbca.org/ for the various track events. You shouldn't be too far from VIR, but we also run at Summit Point Raceway, about five hours north of VIR in West Virginia. They have three circuits, and all but the really short one is also alot of fun. But none are as smooth as VIR!!
Harry