Anheuser-Busch announced at the end of 2006, that it would not be sponsoring the Busch Series in 2008.  Nascar was left to scramble for a new sponsor:  Subway and Walmart were early front runners.  But in the end, Nationwide Insurance stepped in to take the top spot. 

So how much does it cost to sponsor Nascar's second series?  Nascar's lips are sealed on the exact amount, but reports indicate that Nationwide will pay between $10 and $12 million each year.  The sponsorship runs for 7 years to run with the TV deal with ESPN/ABC (all Busch Series races are run on ESPN).  Each year, Nationwide will pay a 6% escalation  fee.  Anheuser-Busch had been paying $8.5 million per year.

In addition, Nationwide will be required to spend $4-$5 million in advertising  on ESPN.  The insurer also has deals with Speedway Motorsports, Inc which cost approximately $4 million per year.  ISC has sponsorship from AAA, and  Nationwide is expected to buy-out those contracts.

The one casualty from the deal is the Busch Series car sponsored by Geico.  Currently Mike Wallace's ride is sponsored through 2009.  At the end of that contract, Geico will need to leave the sport (at least at the Busch level).

Information from Nascar Scene and Jayski's.