For the past ten years, I have been visiting a wide variety of "surplus" or 'salvage" grocery stores. Salvage grocery stores are generally located in and around areas with heavy concentrations of Amish and Mennonites.
Salvage stores stock products purchased from retailers, manufacturers and various jobbers.
Some of the products are overruns, some past dated, and some have the "old" packaging. Some are products that were produced by US manufacturers for the export market but not shipped overseas.
Some people express objections to using past date goods. My approach has always been "it depends." If it is a meat product or a refrigerated product, I am Not excited about it. However, on canned goods - if there are no dents or damage - I have no problems.
Here is an article that I came across this morning:
http://blogs.law.harvard.edu/foodpolicy ... report.pdf