In Boots you just have to buy any two Diet Cokes (£2.36) and you get a free limited edition Nails Inc polish. There are 4 city-themed colours to choose from - Milan (Red), New-York (Fuschia Pink), London (Nude) and Paris (Purply Pink).
I would have had London but they were all out when I was there, so I came away with Paris.
I also bought Barry M Berry Ice Cream
There is also a '20% off Nails Inc Online' offer on the InStyle Magazine website, here.
It has to make you wonder why Nails Inc are so desperate to flog off all of these polishes when they charge £10.50 a bottle in store.
I now have 3 Nails Inc polishes and I got them all for free. They are pretty good but nothing special so I'd rather stick to cheaper brands and get more colours for the same price.