At least in NYC, Trader Joe's is cheaper or comparable with other grocery stores. I spend about half there as I would at a whole foods for a weeks worth of food.

It is actually cheap relative to the quality you get, so a lot of value. A linked article from TFA notes how TJ's is ranked #2 for quality https://clark.com/shopping-retail/cheapest-grocery-stores/ . Sure you can't find the junkiest cheapest things like at a Walmart, but if you need actual food basics like fresh organic produce, organic japanese green tea bags, kefir, and salmon lochs, there's almost nowhere cheaper.

My local "regular" grocery store , Ralphs,has several identical items to Trader Joe's (like the exact same orange chicken, salsa, etc with different labels). The TJs version is universally cheaper. It's a bit more expensive than Walmart and the dollar store but arguably a much better value.

My average bills there are close to shopping at Aldi. Here in Florida at least Publix is significantly more expensive.