Dont forget to grab a cargo net and bungee cords to go with it! A bump in the road has great potential to send contents flying.

Although wald baskets will be more than enough for a modest grocery run, if you're looking for an actual rack with rails/ messenger grade, look at cetma's offerings.

The velo orange porteur rack is the middle ground between those two but it is only compatible with fender mounts unlike the above 2 directly out of the box.