Here's a start: Bruce K. Johnson (Centre College), Peter A. Groothuis (Westminster College), John C. Whitehead (East Carolina University), The Value of Public Goods Generated by a Major League Sports Team: The CVM Approach, Journal of Sports Economics, Vol. 2, No. 1, 6-21 (2001).
This article reports an application of the contingent valuation method to measure the value of public goods generated by a professional sports team, the Pittsburgh Penguins of the National Hockey League. The data and analysis indicate that a major league sports team can produce widely consumed public goods such as civic pride and community spirit and that the value of those public goods may be substantial. However, in the case of the Penguins, the value of the public goods is far less than the cost of building a new arena. Although the analysis of public goods generated by other teams in other cities might lead to different results, the results of this article call into question the widespread practice of government funding of sports stadiums and arenas because it appears that the costs borne by taxpayers exceed the benefits received.
That piece, among others, is cited and discussed in Jordan Rappaport and Chad Wilkerson, What Are the Benefits of Hosting a Major League Sports Franchise?, Federal Reserve Bank of Kansas City Economic Review 2001:1, available at http://kansascityfed.org/publicat/econrev/PDF/1Q01Rapp.pdf
Michael Leeds (Temple University economist) was interviewed yesterday on WDUQ to the effect that the economic impact of the Penguins (like most major sports franchises) is ZERO, but this (I assume) was based on general premises rather than on a study of the Pens per se. He did offer a delightful quote to the effect that professional sports teams represent a "gift" by cities to themselves, valuable (perhaps) for psychic reasons but not justifiable in economic terms.
Unfortunately, I can't find a clip of the interview online.