Along the same lines as the making bread,
espiritkat and I have a bit of a sweet tooth, but a tiny, ridiculously small sample of cheesecake from our downstairs store costs $4.50 each. It's about a 3 inch diameter and 1 inch deep at most, giving us a pitiful amount of cheesecake for our money. So last night I went to the store to buy food and got materials to make the cheesecake filling we like so much.
The basics: 1 x 250g Tararua cream cheese, 1 x 220g (?) Anchor cream, several handfuls of flour, some mandarin juice for flavouring, 2 eggs, 3-4 tablespoons of honey and a similar amount of sugar. Add some bananas or other fruit for garnish. Find a recipe online for free.
Costwise, we probably spent $4 on cream cheese, maybe less; $2.20 for cream, bugger all for the flour and mandarins, maybe a dollar or so for the remaining ingredients. The resulting cheesecake mix - a lot more edible than store bought cheesecake - was at least 3-4 times the amount of cheesecake we would get at the store for $4.50. I cooked it up and left it in a bowl in the fridge to feed our cravings for sweet foods over the course of the next week or so. Its very rich and sweet, so a small amount satisfies.
Again, I really highly recommend making your own processed foods, such as bread/sweets. Its much cheaper and you put personal intention into the food.