If I'm out on a journey and pop into a local Coop or Spar for a sandwich, I nearly always default to tuna mayo / salad or a BLT.
Very boring. I know.
I do like to have a fair helping of tomato slices in whatever I'm buying ......
I think prices have risen a fair bit in recent years - I was charged £4 for a BLT a couple of months back at a village shop in Combe St Nicholas, Somerset and it wasn't all that appetising, certainly not value for money.