eBay has discounted Uber gift cards on sale. You can buy a $50 Uber gift card for just $45 and since these are sold by PayPal Digital Gifts you’ll also receive 5x UR points for your purchase. There’s a limit of 5 gift cards per account.
Don’t forget to use a shopping portal. Ibotta app is probably your best bet for gift card purchases, at 1% cashback.