Nary a national holiday exists without some kind of swag surrounding it, so you can bet your ass there would be miles of Purge-appropriate clothing. Christmas has ugly sweaters, Valentine's Day has teddy bears, St. Paddy's has bus tickets that take you away from urban centers. Come Purge time the seasonal aisle of Walgreens would be filled with Purge-themed merchandise.
Stores would be selling star-spangled .38s and night vision goggles with the year molded in plastic around the frames. And not only in years that make sense, like 2020. Idiots would keep buying them in 2019 and peering through the circle of the nine, looking downright gauche as they murdered people in the night. Stores would stay open as long as possible to cash in on people who always put off their Purge shopping until the last minute.
"Ugh. This is so last year's Purge."
Yet not once in the movies do we see any kind of Purge signage for sales on bulletproof vests with Purge designs embroidered into them. And you just know you'd have like six of those. Your mom would get you one every year for Christmas ... and your birthday ... and Valentine's Day, because she doesn't realize how embarrassing that is.