Limit the cheap carbs
Which costs more: bread, or steak?
If you're a hardcore buffet strategist, you might have a no-carb rule to maximize plate and stomach space, but sometimes those mashed potatoes just look so good.
A more practical rule is to eat only 1 carb per trip, and avoid bread, pasta, and rice entirely until dessert.
Then, you can pile on the bread pudding and cake to your heart's content. Some carbs, like beans, are less filling...but still cheap.
Instead of strolling down the buffet line filling up your precious plate real estate with side items, head directly for the middle.
That's where you'll find the freshly carved turkey, prime rib, cooked-to-order steak, crab legs, and other gourmet goodies.
Start with the main course on every trip, and then fill in with side items, and your dollar will cover a lot more deliciousness.