In the first four days of his first retrospective exhibition, 50 prints starting at £350 were bought by visitors.
And in the same period, the museum sold 400 copies of the £16 catalogue which accompanies the exhibition.
Kelvingrove's shop has a wide range of Vettriano themed items for sale, including a silk scarf with an image of the Singing Butler costing £140, to calendars and fridge magnets.
Glasgow Life trading manager Catherine McGurk admits she is astonished at how quickly the expensive limited edition prints are flying out the door.
She said: "Their popularity has taken us all by surprise."
On Wednesday, 300 signed copies of the exhibition catalogue will be on sale to the public from 10am.
The Vettriano retrospective, which runs until February next year, features 100 of his works, all of which are on loan from private collections.
It includes his most famous work, The Singing Butler, which was sold at Sotheby's in 2004 for close to £750,000 - then a record auction price for a piece by a Scottish artist.