Sounds like the true answer is having a colleague you can buy £1 eggs from.
Eggs are still pretty cheap in the UK, free range ones for £1.50 or so.
For one or a dozen?
It's about €0.35 per organic egg in the Netherlands (€3.19/10 in one store or €5.99/15 at another). The organic eggs have better shells and are so cheap it's not worth bothering with free range eggs, even if you don't care for the chickens. It helps that they're not refrigerated and last a long time, so you don't have to pay for spoilage.