As StageManager mentioned, try a freezer brand or something like
this option from Trader Joe's or a similar store if you don't have Trader Joe's. If you contact them and explain the situation, they may even donate enough product to last you through the run. You could also look at restaurants in your area which might make or serve potato pancakes, they could help you out.
When I was in college my university did a production of Suburbia. One of the main characters drinks something like a dozen beers on stage throughout the course of the show. Two problems - #1 the actor was not 21, #2 he would have been far too intoxicated to stand, let alone act, after that many beers. A national brewery agreed to do a special run of lightly carbonated water in their cans for our production. The actor was sober, and you still got that lovely "cracking a beer" sound inside of a real beer can. Quite a long explanation for the punch line, which is reach out to local companies, they may be willing to help!