Hi DSW, not an exact reply, but hopefully some food for thought ...
Most lines seem to run a fluid pricing policy when operating over this way and the price is derermined by whether your cruise calls into a duty free location such as Gibraltar. If they do, then the prices are often reduced to remain competitive with that port, if they don't then the prices rise again.
As an example, albeit with a different line, our Med cruise this year had a carton of cigarettes at about £22.00, but less than 3 months later, our Baltic cruise had the same cigarettes at £35.00. The only difference was that the Med cruise called into Gibraltar where the prices were about £20.00
If you are calling there, then I would hold off making any purchases on board until you've compared the land prices. Then if the ship is better, buy them on board.
Alan & Katrina
Last: Cunard Queen Victoria January 2016
Next: Oceania Marina June 2016
Then: P&O Oriana August 2016
Then: P&O Oceana December 2016
Golden, Grand(2), Caribbean, Royal, Sea(4+1 aborted)
Adonia(4+2), Arcadia, Artemis(2), Aurora(5), Azura(2), Britannia, Oceana(3), Oriana(12), Ventura(2), Victoria(5)
QM2(2), QE2(9), QV(7), QE, Caronia(2), Minerva, Minerva II, Fred.Olsen(8), NCL Jade, =X= Eclipse, HAL Ryndam, Aza.Journey