4-Pack 4' PD-Compatible USB-C to USB-C braided cables, $5.65 with Prime
At less than $1.50 each, these are the cheapest PD-compatible U.S.-stock USB-C to USB-C cables I could find. Looks like decent strain relief, too.
Plus I love this line from the product listing:
"Don’t worry about no reviews, we are very kind and honest." Well, that’s a relief! LOL