It is a truth universally acknowledged that anything you buy in an airport costs way more than on the other side of security. The airline industry predicts that 28.5 million passengers will fly during the 2017 Thanksgiving season, and the Sunday after the holiday is expected to be the busiest travel day this year. That means lots of waiting in places that want you to pay out the nose for convenience.
Anything you nab on the go while traveling is going to be a wallet-emptier. Those "local" gifts and artworks? You will find something much nicer, cheaper, and more likely to support artists and small businesses at your destination. Forget your travel-sized contact lens solution? The options inside the gate will probably cost more for less product. A candy bar to kill the wait? Even national consumer items can cost more in an airport.
The workaround for this issue is pretty much the same as for anything else: Plan ahead, as much as possible. Use checklists and make sure you have everything you need before coming and going from the airport. That includes toiletries, electronics (and their accompanying power cords), gifts, souvenirs, reading material, and snacks. Some buys may be inescapable, or worth the markup. A stop at the wine bar might be an experience worth paying for; a sit-down meal could help you get re-centered after a stressful trip.
Not everything at the airport is costly, of course — check around for free play areas for kids, or local museum exhibits. You may also find that buying a lounge pass keeps you away from temptation. But by and large, don't beat yourself up for the things you can't control, and do give yourself the structure to control what you can.