I was actually surprised that the 3-lb bags of yellow onions were wiped out at the grocery store the last time I was there... who would have thought people were cooking real food??? They did still have some of the loose yellow onions for sale, so I bought some, along with celery and carrots.
I like to keep fresh ones around for my soups, etc., but can do without and use dried if need be. I do keep dried celery and onion powder in my regular storage, so will only be lacking the carrots... I think I have some dehydrated in LTS, but will have to hunt to find them.