The BBC will be broadcasting coverage on BBC Two, Three and Four and blanket coverage on 6 Music - meaning lesser well-known acts, as well as headliners, are again expected to get a sales boost from a well-received appearance.
Phil Barton, owner of famous West End indie store Sister Ray, admitted, "There's always a surprise every year, Seasick Steve is a good example".
He added, "As an independent we always look at things further down the bill. If people get to see a band like Tame Impala on TV, I think that will make a big difference. Acts like Metronomy and Yuck should do well too, if they get good TV coverage."
Last year Mumford and Sons enjoyed the biggest increase in sales from the Glastonbury effect, with sales of their debut Sign No More being boosted 47.8% week-on-week. Pyramid headliners Gorillaz, Muse and Stevie Wonder also saw impressive increases in sales.
This year's headliners U2, Coldplay and Beyonce are expected to see a similar boost, particularly among the bigger retailers. Beyonce's new album 4 is released this Monday, the day after she headlines the Pyramid Stage, while Coldplay's new single Every Teardrop Is A Waterfall is currently just outside the top 20.
Derry Watkins, owner of Resident Music in Brighton, said it was a case of waiting to see who strikes a chord with TV audiences.
But he also predicted Tame Impala's brand of psychedelic rock could go down well, particularly as the band are appearing twice at Worthy Farm - on the Pyramid Stage and The Park. "They are a great live band, that not a lot of the public are aware of," he said.
Watkins also tipped another Antipodean band, New Zealand's The Naked and Famous, to benefit from a slot at the festival. "They are not just another guitar band, but have that pop element," he said.
The 41st Glastonbury takes place from June 24-26.