Team Values as gleaned from various sources, including the now defunct Financial World, Forbes, and a PDF file on team valuations from the National Sports Law Institute at Marquette. In addition, there is a file that contains popular press reports of team sale prices, including expansion fees. The files either are in MSExcel format or PDF format. So, use your "Save Target As" command to save them to your hard disk.
Financial World/Forbes:
Team valuations only: 1990-2008.
By team by year includes the complete reports by team (revenues, expenses, debt, net, team valuation):
The NLSI Valuation Report: 2001 (PDF)
Team Sale Prices: 1941-present