I think they are usually around £1.99 or £2.50 for 6. Delfland organic do 5 plants for £1.50 - but then they have a hefty mail order charge.
Our farm shop down the road sell excess plants for about £1.20 for half a dozen.
However, apart from Delfland, I find that GC and the farm shop don't sell named varieties, and as I like to know what I am growing I grow from seed.