Here's something I found out trying to min-max gaining. Not only are peanut butter pretzels the ultimate snackfood (only $6 at walmart for a tub of 3220 calories, saltiness balances the sweetness, doesn't need to be refridgerated), you can make them even more dense. If you mix sour cream and salsa con queso jars, you can make a dip to raise it up to 5k calories for a total of $11, you basically make them into DIY Combos. For reference, 2 Little Caesars pizzas would cost $12 for pickup and only be worth 4k calories.