I never scrimp on shoes. I don't go over the top, but at least M&S Footglove or something. I walk at least three miles a day and get shin splints, sprained ankles, etc, whenever I try to go cheap.
I won't buy cheap cheese, but bulk buy whatever mature cheddar is on offer.
Oh and floss. Has to be Oral B satin tape or it splits between my teeth.
Am very happy scouring charity shops and pound shops for clothes, books, CDs, filter coffee, etc, though. My kids have the best dressing up box of any children I know, but it is made up of loads of charity shop finds - jester hats, feather boas, etc. Fun!
I get Douwe Ebert coffee for £1 at the pound shop. Is £4.87 at our local Tesco!!
Also buy market fruit and veggies and go to butcher for cheap meat bulk buys.