I've been expire eating with sourdough. Local lovely bakery sells sourdough loaves got £3 that last me and DH for 5 days.
Bag of flour costs £1.50 or so. I can make two loaves and feed the starter for a week from that. But....so far only one out of seven loaves has Ben edible. I'm treating it as a relatively cheap hobby....
Cakes, if you've got everything in then whipping up a cake is nice, but it's not cheap if you still it out. Coop does a lovely choc cake for 1.99 that it would cost me about £6 to make...
Batch of scones, cheap, but so is a pack from tescos. Artisan m and s scones more expensive.