Getting all my groceries delivered and saving 10% while doing it

This only works in a major metro area, but so far it has been immensely satisfying.

Costco has Doordash gift cards available for 20% off, and lets you buy $200 of them each trip. Doordash has a ton of grocery stores in our area, and makes it really easy to comparison shop for different items. Aldi and Food Lion seem like the best bets overall, but sometimes Harris Teeter has the best deals too.

If you have Dashpass you can get no fee deliveries for spending $60 of credit, which you actually only paid $48 for. Prices are slightly inflated compared to shopping in store and you should tip, so I estimate the real world savings at about 10% once you factor in how much easier comparison shopping is.

You do have to pay for a costco membership (roughly $50 if you do your homework) and get Dashpass ($96), so this will only net out if you spend over $1500 annually on groceries, though of course there is some additional value to having a costco membership and access to doordash. I personally have the Sapphire Reserve card, which has an even bigger fee but pays for Dashpass and gives you $20/mo of credits you can use for doordash groceries. Since all your groceries end up flowing through costco this way it also probably makes sense to pay for an executive membership.

Even with doing this there are a few things that are more than 20% cheaper at walmart, so I still shop there from time to time. If I was lazy and just did all my shopping through doordash though I would still be saving at least 5% over my previous approach, with the benefit of getting all my groceries delivered (and FAST compared to the first party delivery options).

Costco also has Uber Eats gift cards for the same amount; I haven't really explored the options there but I'm guessing those with Uber One can execute basically the same strategy.