My normal source for these has been on vacation for a couple of weeks.  Does anyone know where I can buy a few to hold me over?

Look for a brewing supply store.  Homebrewers use 5 and 6.5 gallon food-grade buckets to ferment beer in.

Beer making shops are good.
 Many fast food places have items shipped to them in food grade buckets and will often give them to you. This could work out for you depending on what you are looking to put in them. (for example pickels are a common item but I would be worried if I was storing liquid in them that my stuff would end up tasting like pickels.
 I have a contact north east of Denver that maybe able to hook you up I will look for her info. Email me and I will look for her info.
 

Beer at Home in Westminster is okay. They're on 121st, about due north of the Avaya Death Star-looking building.

Their buckets will probably be a little pricey, and the lids will be punctured with a hole for an airlock to be fitted.

Also, they're actually a decent homebrew store if you're into that sort of thing.

I usually get them for my Cub Scouts at Jason's Deli.  Please be aware they will smell like what came in them.  The dill pickel buckets are what I usually look for.  Got a garlic one one time and it was not very usefull if you know what I mean.

At the Sams in springs if I go in the day before and ask them to save me some I average about 3 the next day for free