The Sampler is unique in London: a shop where you can taste 80 wines out of the 1,500 on offer. You buy a card (minimum spend £10), then use it to buy 25ml tastes. Samples cost from 30p to £10-plus for the costliest bottles. The wines are terrific at every level. There are around 100 under £10, and the upper reaches include mature classics.
There's also a branch in South Kensington (35 Thurloe Place, SW7 2HP, 7225 5091).