I've also made bags from pet food bags. They do hold up very well. My biggest issues with commercially made bags are those that have no stiff bottom and also that the handles are generally too long for me. I'm 5'2" so if I grab the bags by the top of the handles, the bags practically drag on the ground as I'm carrying them, lol. Then there is the issue of remembering to take them back out to the car and then back into the store for continued use...sigh.