Years ago I'd go infrequently with a friend & spend a fortune. More in stationery & house stuff than food.
i have had my own card for years now, so there's not that 'now or never' feel to it. I can go away, contemplate whether I really need that xyz & kniw I can go back for it if I do want it.
Im vegetarian & I low carb, so my standard 'pop in' shop is
coastal cheddar cheese
homous
olives
almonds
avocados
laundry /cleaning products can be cheaper but aren't always.
some things are a similar price to the supermarket, but if you have storage space are convenient to bulk buy.
Then there's the catering sizes of things like tin foil & baking paper, proper width rolls & a decent length.
I love their Christmas wrapping paper, it's double sided & lively to use.
... tents, bbq, shed, kayak, tv, Mac book, blankets, towels ....
just be warned that something can look small in there, but when you get to the car, suddenly treble in size!!! Or a block of chees looks 'normal' until you get it home to your domestic fridge!!
have fun!