But you haven't made a profit of £150, look at it from a business point of view, vehicle running costs, solutions, purchase of your machinery, any advertising, insurances, replacement or breakage, accountant, national insurance etc etc
If you have a regular wage even min wage you get £200 in your pocket week in week out plus any top up benefits and holiday pay and sick pay etc its not quite the same and that's where people can go wrong.
Shaun