I’ve always assumed, like an idiot, that more expensive things are of better quality. Sometimes that’s true, sometimes it isn’t, never should it be taken at face value.
Trash bags have it written right on the box what their thickness is. Hefty isn’t any heftier than Great Value, which isn’t any greater of a value than Hefty, based on price alone. You can almost always find some generic ones with a decent thickness, and then compare price points for the same thickness.
You can see on the bottom where it says “24 BAGS 7 GAL SIZE” that below it is listed a “mil.”
I always go for at least 0.9 mil. Regardless, in this way, you can compare thickness to thickness and get the cheapest price for the thickness you want.