Not a clue. Values for items like this can flucuate wildly because they are so thinnly traded. To establish value there has to be multiple examples being bought and sold at any given time to arrive at an average.
There are a ton of people on eBay with "Want it Now" requests for the Cheerios Sac! Most of them hoping to buy from someone who doesn't know what they have, I suspect!
That would be me! I did see one fellow offering a $500 reward for one so he wants one much worse than I do!