I think £1 for six is plently. Do you tell the tax man about the income and pay tax on it, do you have any marketing costs, shop rent, liability insurance, parking provision or any of the other things that supermarkets/shops have to pay. You are not paying a margin to your suppler, it is nearly all bottom line. You are probably even getting people to give you their old egg boxes.
Why be greedy, you should be able to sell them all day long at £1/half dozen. Can you take them into an office, send them to school, sell them to neighbours. You have to remember, they may be lovely, but you are competing with the supermarkets in the middle of a recession.
If you need to then cut your overheads by finding a paper shredding company and get you bedding from them or speak to your local shoot and ask them if you can buy some wheat from them. Supplement this with greens not sold from the grocer and give him a box or two of eggs each week in exchange