When older DD was a teen I put $100 dollars in her account for her to use to pick up things for us. Our accounts are linked I would just transfer more if/when she used it. Way back when I was a teen my grandma would give us a blank, signed check and her drivers license to go pick things up for her.Sweet! Our DS is 21 and having him run errands means having to give him one of our debit cards, leaving us without. It's not a great option.
I just checked, $55. I try to have $40 in case I have to buy a tank of gas. I certainly could use my credit card for gas in an emergency, but the cheapest gas station that takes credit cards is 34 cents a gallon more than the cash ones.