This has been discussed on another list, and one lady found 3M disposable ear plugs / hearing protection from one of her local hardware stores.
Rather than the 80 plugs, the package actually uses PAIR as their unit of measure, so the package has 160 plugs, further reducing the price of the substitute to a small fraction of the Pinmoors. She ended up paying $13.45 USD, to get 160 plugs, and they do the same job.