+1 on the powdered milk. I get mine in bulk at Winco or from the Mormon's Bishop's Storehouse, conveniently located behind my Costco. I buy only whole, non-rbst milk, usually at said Costco. I buy 2 gallons and freeze one. When the open gallon gets to about half, I dump in powdered milk and ice cold filtered water. I shake like hell and chill it promptly. This stretches each gallon and no one's the wiser. I only do it once per gallon so no spoilage. I have also been known to obliterate expiration dates with a Sharpie. If I've frozen milk, it can look out of date when it's not.
I occasionally make yogurt. It's easy, but I can also source the big vat (64 oz.) of Mountain High plain yogurt for 3.99 at Costco. I can also find it at Grocery Outlet and occasionally at the 99 Only Stores. I hate anything with pectin or stabilizers, and also avoid highly sweetened stuff. I NEVER pay attention to expiration dates. Yogurt lasts way longer than the date stamped on it, so I never hesitate to stock up when I find a deal.
Next, I make yogurt cheese weekly. Line a colander with unbleached coffee filters and dump in yogurt. Set it into a bowl and cover. Once the whey drains off (save it for cooking), you will be left with yogurt that has a cream cheese-like texture. Eat it plain, lightly sweetened with jam or honey, or season with herbs to make an all-purpose dip. Life changing: cheaper and healthier.
Finally, I buy a LOT of cheese, but only at Grocery Outlet or 99 Only. I only buy brands I know and stock up like crazy when I find a good deal. Yeah, I pretty much ignore expiration dates on cheese, too. Once I open something, I make sure to use it up quickly. If I can't, I grate it and flash-freeze.