The cheapest, as Jim says, has less shot (and I'll add less powder, but only to a lesser degree), in top-quality FREE hulls you scrounged.
Currently folks I shoot with are using NobelSport primers. many like Titewad, Clays, Promo or similar as they are less expensive than some of the old standbys like Red Dot, et al. Just about everyone I know uses a clone wad of some sort from Claybuster, Downrange or similar as they can be almost half the cost of Winchester, Remington and Federal wads. We have reclaimed shot being used, locally-produced shot and then there are those who settle for nothing but top-priced name brand shot. Is there a difference? I'm sure there is, it becomes a question of how it patterns in YOUR gun and whether or not you can actually tell the difference.
There are folks like me who reload a 28 hull until it splits down the middle, and then I shoot with folks who only shoot factory 28's and throw the empties away.
I think you DO have to factor your time somewhat into the equation - especially if you are self-employed or work in a situation where time really IS money.