according to todays Guardian if you buy a Panasonic SD254 breadmaker it will pay for itself in 6 months. It also says the best online price this week is £78.99 at householduk.co.uk.
Since getting mine (secondhand from a lovely MNer who was leaving the country) about 3 months ago I've bought 2 loaves of bread.
Ask around your friends, see if any have one they don't use and borrow it to see how you go.
Oh, and Lidl breadflour is about 50p a bag and is better than Sainsburys