2pk 30,000mAh Power Banks $28

This 2-Pack of 30,000mAh USB-C 22.5W Powerbanks with Built-in Cables falls to $27.99 at Woot. Or, get a 3-pack for $38.99. Sign in to an Amazon Prime account for free shipping. Otherwise, it adds $6. You'd pay $30-$40 for two elsewhere. They have USB-C and lightning cables built in, so you won't have to worry about grabbing a cable before you leave the house.