New York’s attorney general, the same man whose 2005 payola investigation resulted in Sony BMG coughing up $10 million as well as a promise to never conduct pay-for-play activities again, is looking into why most music download services charge the same price. Namely, the price of 99 cents per song.

Spitzer is looking for evidence of collusion between the major labels and is very interested in what is called a “most-favored nation” clause included in contracts between the majors and many online services, according to the Los Angeles Times. Such a clause acts as a price guarantee, ensuring that if a label makes a better deal with an online service than competing labels, all other label agreements will upgrade to the new agreement’s specs.

Spitzer’s latest record label activities surfaced late last year when Warner Music Group mentioned a subpoena in a regulatory filing. At the same time, The Wall Street Journal reported that Sony BMG and Universal Music Group had each received subpoenas.

Although Spitzer’s office has yet to comment on the subpoenas, the Times said people familiar with the probe have confirmed that it’s the “most-favored nation” aspect of online contracts that has piqued the attorney general’s interest.

While the Times reports that music industry executives contacted for its story refused to go on record due to the ongoing investigation, the paper also noted that many execs said the most-favored clauses are “appropriate.”

“The music industry wanted to establish the online marketplace as quickly as possible, but we didn’t want to get bogged down in debates over prices,” said one anonymous music industry exec. “These clauses let us create a viable marketplace quickly, and then make sure all musical artists are equally compensated.”

Of course, those associated with the other side of the bargaining table had a different opinion.

Jonathan Potter, executive director of the Digital Media Association, which reps several hi-tech companies, including Apple, RealNetworks and Yahoo!, said the labels had insisted the most-favored clauses be included in their online licensing deals, “Collusion has never been known to lower prices,” said Potter.