Homemade bread, pizza, jam, granola. Also any pastry, sauces. I guess I try and minimise supermarket mark-up whilst buying the best quality (organic, but not necessarily branded) ingredients I can.
Grow and freeze as much fruit and veg as I can and buy seasonally from honesty stalls.
Meat in bulk from local organic and ethical farmers/hunters (for family, I'm veggie)
Tins, beans etc - own brand organic so the cheapest but I do sometimes go to a foreign foods stores to bulk buy herbs, spices, rice, tahini, coconut oil etc which usully works out better and much cheaper.
I made a decision a few years ago never to buy shop-bought desserts (ok, very rarely); either make my own (eg fruit crumble, meringue, sponge etc) or it's fruit/honey/yoghurt or fruit plain.
Waitrose oat biscuits - no palm oil and cheaper/better than branded. I am actually addicted and don't eat any other sorts of biscuits!
Honey from DHs bees (all supermarket honey tested independently contains sugar syrup so honey from beekeepers is the only sort worth the name)
Books 2nd hand or library. Clothes charity store, home-made or adapted.
A lot of the items mentioned could just not be bought, thereby saving money if that is the impetus. Like takeaways - we might get an excellent Indian once yearly.