Team Values as gleaned from various sources, including the now defunct Financial World magazine, Forbes, and a PDF file on team valuations from the National Sports Law Institute at Marquette. As best I can deduce, the series skipped 1997-98 in the move from Financial World to Forbes. I base this on the notations that the 1998-99 valuations are based data up to 1997-98 while the last Financial World entry noted that it was based on data up to the 1996 season including the playoffs. 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:
Index file: 1991 through 1997
By team by year:
Forbes:
Index file: 1999 through 2008
By team by year:
The NLSI Valuation Report: 2001
Team Sale Prices: 1951-present