Limited edition copies of Blur's first new single in seven years are selling for up to £200 on internet auction site eBay.
Just 1,000 copies of Fool's Day were released on 7" vinyl to mark Record Store Day last weekend.
But within hours of it hitting shop shelves, copies were listed for sale on the eBay site.
The amount fans have paid for the records ranges from £90 to £200, with many auctions still ongoing.
The band have also put the track up on their website so that fans can download it for free.
Blur closed Glastonbury 2009 with a set on the Pyramid stage
Blur's manager Chris Morrison said it was important that the song was made available legally, "to avoid fans having to illegally obtain an inferior copy from pirate sites".
Damon Albarn, Graham Coxon, Alex James and Dave Rowntree recorded the track at a London studio earlier this month.
Fool's Day is the first new material from all four members of Blur since Battery In Your Leg from the 2003 album Think Tank.
It follows last summer's hugely successful reunion tour, with headline slots at festivals including Glastonbury and T in the Park.