The official Trump campaign store isn't around anymore. You can donate directly to Trump's Save America PAC at www.donaldjtrump.com but you won't get any merch for it. Most MAGA gear you'll find from online retailers is bootleg merchandise that Trump doesn't see a dime of.

Also, be aware that the RNC has vowed that they won't stop using Trump's name and likeness for fundraising purposes despite Trump sending them a cease-and-desist notice. Make sure you research who is actually selling Trump campaign gear.