In a few cases where you are making something once it can be more expensive because you can't buy one teaspoon of a spice or have to buy more than you need. Initially there is cookware to purchase and upkeep, and things like that.

But if you make more than one meal from the same prep, or serve multiple people, eating at home is almost always cheaper in the long run as nearly everything in the kitchen lasts for years at a minimum and often a lifetime. Especially if you plan long term and get staples in bulk when it makes sense and buy more expensive things when they are on sale.