Team Values as gleaned from various sources, including 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:
All teams, all years: 1991-97
By team by year:
Forbes:
All teams, all years: 1999-2005, 2008
By team by year:
The NLSI Valuation Report: 2001
Team Sale Prices: 1920-present